I’ve found it’s really a combination of both.
You can take your favorite shaft and it won’t work the same with every club head since there are so many variations in weighting and loft.
Realistically, they can go out and buy a club from last year or the year before for a steep discount and just get fitted for the proper shaft for that club head.
A great book to read on the whole subject of equipment is “The Right Sticks” by Tom Wishon, who really is a genius when it comes to golf equipment.
Here’s a link to the book on Amazon.
http://www.amazon.com/Right-Sticks-Equipment-Myths-Could/dp/1587264986/ref=pd_sim_b_1
The battle was overcoming the impression that what was hitting the ball (the head) was the most important part of the equipment.