Hi guys, so after working with GPT/Codex for different styles of work since its release, I thought I would try and get a grasp on the models, what is best used for what. I asked GPT chat to analyse all my work since explicitly using the 5.6 models for all recent work, analyse all my projects and work. Then tell me the best way of using each model and what for based on my work and what I have produced, here is the scope.
I would say I have been using the models in the way below about 50% correctly, sometimes I do forget to switch but thats on me.
# Recommended operating model
As of **17 July 2026**, the GPT-5.6 family consists of:
* **Sol** — highest-capability model for complex professional work.
* **Terra** — balanced capability, speed, and cost.
* **Luna** — fastest and lowest-cost GPT-5.6 option.
* **Sol Pro** — highest-quality ChatGPT option for especially difficult or long-running tasks. [OpenAI](https://openai.com/index/gpt-5-6/?utm_source=chatgpt.com)
Your best workflow is not to select one model permanently. Use an **escalation ladder**:
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Start with the cheapest level likely to succeed. Escalate when the task involves ambiguity, architectural decisions, multiple source documents, security, financial consequences, or a difficult final review.
# Use the right ChatGPT surface first
| Surface |
Best use |
| **Chat** |
Questions, discussion, brainstorming, quick rewrites and decisions |
| **Work** |
Research, guides, reports, policies, spreadsheets, documents, presentations and finished deliverables |
| **Codex** |
Working directly in repositories, implementing features, fixing bugs, testing and shipping code |
The new desktop application combines Chat, Work, and Codex. OpenAI positions Work for research and finished deliverables, and Codex for software development. [OpenAI Help Center](https://help.openai.com/en/articles/20001275-chatgpt-work-and-codex?utm_source=chatgpt.com)
# 1. Office work
# Your default: Work + Terra, medium effort
Use this for:
* First drafts of guides and procedures
* Internal reports
* Meeting summaries and action plans
* Reformatting existing material
* Turning notes into structured documents
* Comparing versions of a policy
* Routine franchise documentation
* Training materials and checklists
Terra is intended to balance capability and efficiency, making it the sensible default for normal professional workloads. [OpenAI](https://openai.com/index/gpt-5-6/?utm_source=chatgpt.com)
# Example instruction
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# Escalate to Sol High for:
* Policies with interdependent rules
* Sensitive employee or customer-facing documents
* Executive or board reports
* Reconciling conflicting source documents
* Analysing operational risks
* Producing recommendations from large evidence sets
* Documents where factual consistency matters more than speed
Sol is designed for complex knowledge work, research, design, coding and multi-step professional tasks. In ordinary ChatGPT, Medium, High and Extra High are powered by GPT-5.6 Sol. [OpenAI Help Center](https://help.openai.com/en/articles/20001354-gpt-56-in-chatgpt?utm_source=chatgpt.com)
# Use Sol Pro or Extra High for:
* Final policy audits
* Major strategic reports
* High-stakes recommendations
* Cross-document compliance analysis
* A deliverable that must survive senior-management scrutiny
* Finding contradictions, edge cases and unintended consequences
Do not use Pro for routine prose polishing. Its value is in difficult reasoning and longer workflows, not ordinary drafting. [OpenAI Help Center](https://help.openai.com/en/articles/20001354-gpt-56-in-chatgpt?utm_source=chatgpt.com)
# Use Luna only for mechanical office work
Appropriate examples:
* Categorising comments
* Extracting fields from repeated documents
* Formatting headings
* Converting paragraphs into tables
* Producing many short variants
* Basic summaries
* Renaming or standardising terminology
Avoid Luna as the primary author of policies, procedures or important recommendations. It is optimised for speed and cost-sensitive, high-volume work. [OpenAI Developers](https://developers.openai.com/api/docs/models/gpt-5.6-luna?utm_source=chatgpt.com)
# Best office workflow
- **Terra:** build the first complete document.
- **Sol High:** challenge the logic, identify missing cases and improve structure.
- **Sol or Terra:** apply final edits.
- **Separate Sol review:** inspect the finished document against a defined checklist.
That final review should be a separate prompt or task so the model critiques the deliverable rather than defending its earlier decisions.
# 2. Coding
# Use Codex, not ordinary Chat, whenever files must change
Codex is specifically designed to write, review and ship code, including features, complex refactors, migrations, pull requests and code reviews. [OpenAI Help Center](https://help.openai.com/en/articles/11369540-using-codex-with-your-chatgpt-plan?utm_source=chatgpt.com)
# Your default: Codex + Terra, medium effort
Use it for:
* Small and medium refactors
* Adding tests
* Fixing straightforward bugs
* Chrome extension features
* CRUD screens
* API endpoints
* Documentation
* TypeScript cleanup
* Component extraction
* Accessibility improvements
* Routine database migrations
* SEO metadata implementation
Terra should handle the majority of well-scoped engineering tickets.
# Give Codex a verification contract
Instead of:
>
Use:
>
# Use Codex + Sol High for:
* New macOS app architecture
* Swift or SwiftUI state-management decisions
* Complex Chrome extension architecture
* Stripe billing and webhook systems
* Supabase authentication and row-level security
* Database schema design
* Security-sensitive integrations
* Difficult production bugs
* Large cross-cutting refactors
* Performance diagnosis
* Offline synchronisation
* Complex background processes
* Professional design-system implementation
These tasks involve multiple interacting systems and costly failure modes. Sol is the appropriate tier for complex coding and agentic tool use. [OpenAI](https://openai.com/index/gpt-5-6/?utm_source=chatgpt.com)
# Use Max or Ultra selectively
In Work and Codex, GPT-5.6 supports a `max` reasoning setting. Ultra can use subagents for more complex work and is available on eligible plans. [OpenAI](https://openai.com/index/gpt-5-6/?utm_source=chatgpt.com)
Use it for:
* Building a substantial application from a specification
* Repository-wide migrations
* Multi-agent code review
* Investigating an intermittent systems bug
* Major framework upgrades
* Release-readiness audits
* Parallel frontend, backend, test and security workstreams
* Understanding an unfamiliar large codebase
Do not use Ultra for changing a button label or extracting a component.
# Use Luna for controlled, repetitive code changes
Good tasks include:
* Renaming symbols across files
* Generating fixtures
* Adding repetitive test cases
* Updating import paths
* Mechanical CSS conversions
* Writing simple schemas
* Creating boilerplate files
* Standardising comments or documentation
Require tests or deterministic validation because repetitive changes can still produce widespread errors.
# Stripe and Supabase rule
For these integrations, your default should be:
>
Specifically ask for:
* Trust boundaries
* Authentication and authorisation rules
* Webhook signature verification
* Idempotency
* Database constraints
* Row-level security policies
* Retry behaviour
* Race conditions
* Logging without leaking secrets
* Test-mode versus production-mode separation
* Rollback strategy
Do not treat a working happy-path demo as a finished integration.
# UX/UI design rule
Divide design work into three stages:
# 1. Product definition — Work or Chat + Sol High
Use Sol to define:
* Users and jobs to be done
* Information architecture
* User journeys
* Interaction states
* Empty, loading, error and success states
* Accessibility requirements
* Responsive behaviour
* Visual hierarchy
# 2. Visual exploration — Image generation
Use image generation for:
* Mood boards
* Visual directions
* Interface concepts
* Brand exploration
* Marketing compositions
Treat generated UI images as design references, not implementation specifications.
# 3. Implementation — Codex + Sol or Terra
Use Sol for the foundational system and difficult interactions. Use Terra for component-by-component execution once the design language is established.
A strong prompt should include screenshots, dimensions, typography, spacing rules, state requirements and acceptance criteria—not merely “make it professional.”
# SEO
Use **Work + Terra** for:
* Keyword clustering
* Content inventories
* Metadata
* Internal-link recommendations
* Content briefs
* Structured-data planning
* Page comparison
Use **Work + Sol High with web research** for:
* Search-intent analysis
* Competitive research
* Technical SEO diagnosis
* Site architecture
* Programmatic SEO strategy
* Evaluating traffic losses
* Prioritising opportunities
SEO depends on current search results, competitors and platform guidance, so explicitly require current web research and dated sources.
# 3. General use
# Research
# Terra medium
Use for:
* Initial research
* Product comparisons
* Straightforward market summaries
* Gathering sources
* Producing a decision table
* Explaining unfamiliar subjects
# Sol High
Use for:
* Conflicting evidence
* Strategic recommendations
* Long research reports
* Niche or technical subjects
* Separating facts from inference
* Identifying limitations in available evidence
* Combining many sources into one position
For substantial research, use **Work**, provide the exact decision you are making, and require citations beside the relevant claims.
A useful formulation is:
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# Brainstorming
Use **Instant or Terra** for divergent thinking:
* Names
* Concepts
* feature possibilities
* Campaign ideas
* Alternative approaches
Then use **Sol High** for convergence:
* Score the options
* Expose weaknesses
* Combine the strongest elements
* Select one direction
* Create an execution plan
Using Sol for every raw brainstorming round can produce overdeveloped ideas too early. Use the faster models to create range, then Sol to exercise judgement.
# Image generation
Use Sol or Terra to create the **creative brief**, then invoke image generation. The quality of the brief matters more than repeatedly rewriting a one-line prompt.
Specify:
* Subject
* Intended use
* Composition
* Camera or visual viewpoint
* Lighting
* Materials
* Colour system
* Brand tone
* Aspect ratio
* Required text
* Prohibited elements
* Reference-image priorities
For commercial work, generate several deliberately different directions rather than minor variations of one composition.
# Your practical daily defaults
| Situation |
Recommended choice |
| Quick question or rewrite |
**Chat — Instant** |
| Normal guide, report or procedure |
**Work — Terra Medium** |
| Important policy or strategic report |
**Work — Sol High** |
| Final high-stakes document review |
**Sol Extra High or Pro** |
| Small code change |
**Codex — Terra Medium** |
| New feature across several files |
**Codex — Sol High** |
| Stripe, Supabase, auth or security |
**Codex — Sol High** |
| Major application build |
**Codex — Sol Max/Ultra** |
| Repetitive code or document processing |
**Luna** |
| Fast research |
**Work — Terra Medium** |
| Deep research and recommendations |
**Work — Sol High** |
| Raw brainstorming |
**Instant or Terra** |
| Selecting and developing the best idea |
**Sol High** |
| Visual exploration |
**Image generation with a detailed brief** |
# The simplest rule to remember
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