I usually can handle it if there is at least some improvement. I can't stand going for an hour and seeing a 1-2% increase. That's just a silly waste of time.

I also find myself cussing every time I learn from my mistakes and only get a 1% improvement. I find myself keeping track whenever that happens and think to myself well if I'd have gotten 3% on all of those I'd be at 95% now, almost done! Instead I'm only at 89% Fuck!