I forgot to add Whirlifloc to a recent small batch boil. Tempted to fuggedaboudit, but one of the reasons for my small batch was to improve clarity in an experimental beer. I had already turned the burner off, but turned it back on and threw in the appropriate amount of Whirlifloc. I brought it back to a wimpy boil for three minutes or so, hoping to at least have done a little something in the direction of better clarity. Since it was a small batch and I was boiling on my stovetop, my wort was already pretty reduced and I didn't want to lose any more to evaporation, hence the quick, wimpy boil when I knew better. Still, I was really surprised not to see any effect whatsoever from the Whirlifloc either right away or a week into primary. I'm aware that one doesn't want to add Whirlifloc too soon or risk denaturing it, but it would appear that a hard boil really is key here, as well as the recommended duration of 10 minutes in the boil.