I reuse them but keep an eye on how hard they are to open. When they get too easy then they could open by themselves if the chain slacks in use. BTDT. So I'll estimate you can reuse the KMC links 3 or 4 times then into the recycling. YMMV. I use a plier like tool to "open" them.
I agree about removing the chain. Mine get cleaned by a real good sloshing in milk bottle with a couple of inches of OMS, then dry out in the sun.