I don't like the Check Required flaw, and I try not to use it on my PCs unless I actually *want* the power to fail somewhat often. In most cases, I will disallow the power on PCs when I GM unless the player is likely to fail somewhat often. The reason is as already described in this thread: a flaw that doesn't limit a power is not a flaw. In most cases, players won't take this flaw unless their skill is so high they will never fail, and so the flaw is just a way to save points. It's lame.