I try to think about it by counting catches, not misses. If my son goes in the potty 2x/day (and really, he does waaaay better than that, even during not-so-good times...and now he's nearly a grad!), then I save washing OVER SEVEN HUNDRED DIAPERS A YEAR.
Yeah, do that math.
So that's how I keep from getting frustrated during times when there's suddenly lots of poo in diapers.
Oh, and also, it does always pass, and suddenly (usually when I'm just about to...