No fitters around me, so I am with sdandrea1. I tinker until something feels right and works.
I haven't bought a driver or driver shaft in a long time. I pulled out my Adams Speedline Super LS from the garage and pulled the x-flex shaft that never felt right. I installed a shaft from a bunch that was sent to me by a member here or the old site. The one i stuck in there was a Powerstrike "Shafts by Precision Components U.S.A. Never heard of the shaft and it is actually stepped. Basically has 3 different sections, thick at the butt, stepped down smaller in the mid section, then stepped down again to the tip section. This shaft was MONEY. Great launch, good roll and forgiving. Sadly it snapped right at the adapter on Wednesday after hitting a driver right down the middle. Just drilled out the adapter and reinstalled. Hopefully the 1/2" tip I lost won't make much diffrence.