BMW Repair: brakes, automotive mechanics, timeframe

Question
how long generally does it take to replace a set of brakes and drums?

Answer
It all depends on experience and what type of car.
if your talking about having it done, automotive mechanics have whats called Blue book, it displays the amount of hours required to perform a repair, anything beyond that is sore luck for them since they don't have the experience required to complete the task in the alloted timeframe.
-cheers