I clean them after about 500 rounds. I take the seating stem out and make sure it's clean, as well as the powder through expander on my LNL, primer tray, etc. Gunk will build up and, I find the press just runs better if everything has been cleaned periodically. I like the Hornady One-Shot cleaner and dry lube. Old bore snakes also work well for the insides of the dies, etc.