May be I am over-doing it, but I do leave it for over a day. What I noticed is that they don't eat much during the first day, and they really start to eat during the second day. By the end of 3rd day, there's nothing left for me to remove. In fact, I never remove any vegetables once it goes into the tank, so far...
"They" in this case are bristlenose plecos and they have been growing fine for the past one year or so...