Talking diffs, I clean mine out and reassembly either every week or every other. I race a clean indoor track twice a week, with maybe a practice day in there. About 15-20 packs a week. Diffs need cleaned out quite often to remain smooth. I'll flip the rings around when one side grooves up and is not smooth and will replace as needed. Rings are cheap. A smooth diff is very important and mine is always that, even when tight.
Smooth shocks and diffs are your friend.