Bearings should last a long long time. People usually screw them up when they try to take them out, lol!!
One thing I notice after fishing a local trib is that my guides are super dirty.. If the reel isn't soaked with egg juice, I'll usually just clean the inserts with a q-tip and a bit of soap. As for the reel I usually give it a good once over after every few trips.. If it's not dirty, I don't clean it. One drop of Singers Sewing machine oil per bearing should last an entire season if I don't dunk it over and over.
I personally try and not to dunk my reels, but if it happens, it happens.. Not a big deal.