Been wrenching since 1982 either full time or part time. Currently I am wrenching full time as my final farewell to the working world. Basic tune ups that cover adjustments takes me 45 minutes on average. The only time I have spent only 30 minutes on a basic tune up is a new bike tune up. My method is well rehearsed and never varies as I find it is the most efficient way to go about a tune up. A full tune up that includes repack of hubs and headset along with a drive train clean is a 2-3 hour process. Every shop I know of usually undercharges for this service .