It seems like you only see it called at the end of the match, when the guy leading is backing up, with 20 seconds left. 

Most of the time he has been stalling the whole period and he doesn’t get called for it until the end.  Refs let the wrestler stall for about 1:30 before calling it.  I think he gets ten seconds to make a "move" or he gets called for stalling. 

It is not stalling if you hold your arms to your side when the guy is trying to bar you.  Many refs say this is stalling, because he is not moving.  But technically he is not stalling, he is trying not to get bared.

Heavyweights could use this warning a lot more too.  Yeah they are heavyweights, but they have still got to move.

I hope this gets called more often then is does now.