I've spent a LOT of time in archery shops and box stores like Cabelas over the past several years while working events for BowTech and Diamond. I've seen a lot of great techs in both pro shops and box stores, and I've seen a lot of terrible work come out of both as well. It really depends on each individual store and who they have on staff. Take a look at the bows they have on the rack for display, that will tell you a lot about how well they setup bows.
I bought my first at BassPro. What a mess. Went to a well respected shop for help and wound up with an almost set up bow. Finally went to a local guy and he set me straight. Took the time and explained everything. He was well worth the time and the money.