I bought a little bunny/The Seven Substitute Shinobi

[drakensis]

(nods) So ka, so ka. Communication is very important for teamwork, you should let your sensei know about these sorts of plans so he doesn't waste valuable time on redundant effort.

Or don't let him know - to make sure that he does waste effort on redundant effort while you are otherwise engaged.
What do you suppose the three of them might have been doing while Kakashi was engaged in calculating the bill?
And what might have happened to Zabuza (and arguably Haku) since circumstances differed so dramatically?
D for Drakensis

You're only young once, but immaturity is forever.