Yuper that whats works for me.
In my experiences you can not reallllyyy plan things out ahead of time that will always be completed as to fit to finish based on your original design ideals so I usually land up with is 80% of my original concept and 20% derived through iterations.
You will hear the word iterations used ALOT as the result usually arrives through the process of practical application and evaluation and player models is a good example as you can not predict if the design is a fit until you have it moving around in 3d space.
The overall ideal though is to get what you have as a “workable” concept into the game environment as soon as possible so you can see visually see how it “all” scales relative to one object to another and focus more on the source chain that makes it an easy task to replace “stuff” that does not fit with the design.