I think it's a horrible idea.
People who don't know any better spend way too much time worrying about shotgun patterns and stocks and whatever. The problem is that those things are done slowly, under controlled circumstances. The test on a shotgun is to go shoot it and see if what you're shooting at breaks or falls. Don't worry about taking careful aim, point and shoot. If what you aim ait goes down, the gun works for you. If it doesn't, it's time to sell.
Stock fitting is perhaps moderately appropriate when you've reached the level of seriously competetive shooter. For 99% of guys it's hype.