With my LBS I don't give them much business only buy the odd can of lube there. Most mechanicy thing they do for me is pop headset lower races on and off forks for me when they get stuck. The chief mechanic in there loves a little retro chat. when I took a pair of RC36's in he loved it, bounced them up and down, told me how he ran a set until very recently and mention that that the early ones had a problem with circlips failing.
Completely depends on the LBS. luckily that one is also the nearest to me - quite often pop in when I'm walking the dog
I think this is part of it, even if you have a local with a mechanic that has been round the block a few times, his services are not that often called upon as we all do the work ourselves and very rarely need his assistance, hence most places won't (or can't afford to) pay for that experience but rather the local trainee who looks at a square tapered bb and asks what is it ?