When the LBS does the fit service, they'll make changes to the stock bike based on your size, flexibility etc. Then, it's not like they'll send you off and tell you never to come back if there's issues. They should give you a window of time to come back with feedback and make additional refinements. So, after the fit, you'll take the bike home and go for some rides. If you find something's not feeling right, you can go back with the specific issue (assuming there's not just a problem with your body!) and they should make additional refinements until the problems that can be addressed by the bike fit have been addressed. YMMV but that's my experience.