On my Glocks, I fully strip the lower frame every cleaning (except mag release and slide stop).
I strip my slide every 1K rounds or so.
The slide will build up a lot of brass shavings. I don't know how many are needed to cause a malfunction, probably many thousand rounds, but I like to keep it clean.
"Now remember, things look bad and it looks like you're not gonna make it, then you gotta get mean. I mean plumb, mad-dog mean. 'Cause if you lose your head and you give up then you neither live nor win. That's just the way it is". Clint Eastwood as Josey Wales