Measure the draw length. It's the most important measurement of all of them.
You can change brace height by advancing or retarding the cams. You can also change draw weight and draw length.
The reason I don't think they are necessary is that if a person is so anal about things then twisting the cable or strings is necessary to tweak the draw length for the most proper fit. Making such an adjustment will more than likely alter the position of the cam. In my estimation this is much more important than a few fps of performance, and what little bit of nock travel it may cause can easily be compensated for during tuning.
How many people do you know or hear of that know how fast their bow shoots? Conversely how many people do you know that know to the last
1/8" what the draw length of their bow is?
If You're Not Living on the Edge You're Taking Up Too Much Space
Martin Gold Plus Staff Shooter
PSAA Life member, UBP Life member
PADI AOW Diver