Back when I was a noob I once forgot to add Irish Moss to the boil, and I'm all "Holy Crap! Should I pitch it and start over?" And the club prez told me don't worry about it. And he was right. I couldn't tell that the brew was more cloudy than any other brew that I made before or since!.
I did screw one batch up royally: I hit 165F at mash in on a partigyle ESB. My brew log does not say how that happened, just that it did. I immediately quenched the mash with cold water, but the damage was done. The ESB only got to FG 1.030, and the small beer was like water. Both were completely undrinkable, and I tossed them after fretting about it for two weeks.
I think that brewing beer is a bit like fighting the Hydra: You can't take it all on at once. Attack the head that is the most threatening at the moment, and then the next one, and the next one. And pretty soon the Hydra doesn't have so many heads.
Charlie