The category says it all... club fitting works! I've seen a +20% increase in FWH without making any swing changes because I was fit for the shaft in my driver.
I signed up for my Titleist Thursday fitting at Metropolitan Golf Links (Oakland, CA), and Jon Worrall was top notch! (The identities of the shaft manufactures have been protected... because what worked for me, won't necessarily work for you! GET FIT!) =P
I went into the fitting already knowing my driver numbers (speed, efficiency, carry, launch, spin), and what I was looking to accomplish from the fitting. That goal, was to lower my launch angle (was +-16*), and spin (was 2.6k to 2.8k). With an attack angle of about +2*, I told Jon what I was looking for.
After warming up, we started looking at my numbers with my current setup with TrackMan, and from the first ball, Jon agreed that my launch was high. We took some sample data, then went into the fitting for the 917D3 (currently playing a 913D3). We spent the majority of time of the shaft fitting, since the weight adjustments are the fine-tuning pieces. I hit a number of different shafts, and in different flexes. I told Jon, that the reason why I liked my current shaft, was because of the high kick-point, which gave a stable feeling through the impact zone. Jon took that feedback, and revised the shaft selection to provide that feel that I was looking for, not necessarily with the same kick-point, but with lower torque. THIS is where getting fit is justified, because my shaft selection would have been limited to a certain pool of brands, just based on my experience and knowledge. Jon gave me a shaft with the feel that I was looking for, and with the reduced spin, really tightened up my dispersion.
Mission accomplished! My launch was lowered to +-14* and spin down towards 2.4k - 2.5k. Before I was only hitting about 50% FWH, and since then have increased to +70% FWH without changing any mechanics. Obviously, with better ball flight and more fairways hit, I've gained distance off the tee as a product of the more optimized numbers, and more of the short grass.
Cheers!