It is depending on a person's exercise abilities and how long the person is able to resist. It is not something that is not possible but surely it is not something that everyone can do without previous exercise time and experience.
Somebody said that it took him 30 minutes for 3000 push-ups which means that he did 1000 push-ups per 10 minutes. I think that it takes longer.
My opinion is that for 3000 push-ups and 2000 could be 1 hour of workout.
