I have 10 players that i use on a regular basis in one room how often is best to unplug one then put another one back in use for a while?

Ten players? That's a lot. You might have to change out every two months or so just to make sure none of them go more than two years without being used.

just bought 2 more so its around 10 not counting the 104s in a closet.

I have six Pioneers and use a different one each week to play my discs.
Ten is a pretty awesome collection. gotta be honest though, the six cost less than $1,000 to buy. the first one, CLD2950 cost me 600, some others cost me under eighty bucks