Vacation Leave

What would be a reasonable amount of time for an opponent to take a vacation/holiday leave in a tournament? When the vacation mode is on, the opponent is protected from 'timeout'... But for how long?

Before responding with the obvious answer, "For as long the opponent needs to be away!" I should point out that this is a feature that could be abused and extend the waiting time indefinitely.

You are allowed to use 36 days per calendar year.
Unused days from one year do not carry over to the next year.
Timeout and timebank continue to deplete while on vacation status.

I believe this information to be correct.