If today were half as good as tomorrow is supposed to be, it would probably be twice as good as yesterday was.
Ninety percent of the time things will turn out worse than you expect. The other 10 percent of the time you had no right to expect so much.
One-tenth of the participants produce over one-third of the output. Increasing the number of participants merely reduces the average output.
Most projects start out slowly, and then sort of taper off.