There is only one reason to remove wings for a paint job and that is if you don't have a controlled, filtered, and propperly vented place big enough to fit an entire airplane in. Restorations , rebuilds, and already disassembled or new projects are the only thing we paint in pieces. If a plane flys into my facility for a standard paint job, we remove the control surfaces, cowling, plastic or fiberglass parts, most doors, and any thing else that comes off easily that can be painted in our automotive (14' x 27' semi down draft) booth. I can tell you for a fact that not all AP mechanics are painters. Applying paint and being a trained , skilled, experienced painter are two different things. If a guy has 20 years experience as an AP and has painted a hand full of planes in that time, he is not a current, experienced painter. I'm not saying he can't do the job, but I will gaurentee he won't have the same skills and knowledge of a guy who has painted every day for the past 20 years. Being current and up to date with painting is kind of like flying, if you only fly 5 hrs in 20 years you will not be as shap as a guy who flys everyday for a living for 20 years.