Full disclosure: I’m the founder of StretchWell, an assisted-stretching and personal-training studio in Belgrade. This is general education, not a diagnosis or a sales offer.
A lot of people treat flexibility as a test of how much discomfort they can tolerate. I think that is usually the wrong target.
Static stretching and PNF-style contract-relax work can both help improve range of motion when they are practiced consistently. PNF is not magic and it is not necessarily superior for every person, but it gives some people a useful way to explore end range with more control.
A simple contract–relax sequence looks like this:

1. Move into a comfortable stretch-not sharp pain.

2. Gently contract the target area for a few seconds at a low effort.

3. Relax, breathe normally, and see whether a slightly larger comfortable range is available.

4. Repeat only a couple of times; more intensity is not automatically better.

The useful question is not “How far can I force this today?” It is “Can I return to this movement consistently, with control, next week?”If a position produces sharp, electric, spreading, or worsening symptoms, stop rather than trying to stretch through it.
Assisted stretching can be useful when it helps someone learn control and comfort in a position they cannot manage alone-but a good session should build independence, not dependence.