In the later forms, I don't even know if "changes" is the right word.
With that said, I think you're in a fairly unique spot at your rank. I'm going to
pretend for a minute that you're a lower belt than I am. You would be expected to do the form our way, for a few reasons:
- To help get ready for your next test
- So that all of the students are being taught the same way
Now, I don't honestly know how it works when I high-ranking person goes to a new school. Since I've gotten my black belt, we've only had one student come in who was a higher rank than me, and he was a returning student. So I'm not really sure of the dynamic.
I would argue that (for the most part) there isn't another context for these forms. I don't see them as a practical training tool; more of an exercise and a performance. The place they are most applicable is on a belt test or form competition. Since those are standardized by Kukkiwon and World Taekwondo, there is a correct way of doing things.
As to the "flow", the form can "flow" with different techniques, but I don't feel the forms are grounded in any realistic choreography to begin with.
For the most part, I think that time spent on forms is better spent perfecting the details to have a better performance on your test or competition.