I brought my bike into Kyle's shop to fix the noise in my rear wheel. The mechanic suggested that I need to overhauled the rear hub for $30. The next day the noise came back even worst. I brought it back to the shop and they said it was the freewheel driver not the hub that needed to be work on and it would cost me extra $30 to overhauled it again plus the part to fix it. At this point I walked out of the shop and took my bike to David's world. The mechanic at David's world took a quick look at the rear hub and indicated that the axle was put back too tight when Kyle's mechanics were working on it and further identify the issue. I ended up paying David's world the $30 plus part to fix my bike, but the major different is that David's World has 30 Days services warranty claim. If you have any issue with your bike within the 30 days the service was performed you can bring it back and they will fix it no question ask.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.