Nothingness: I agree with you.
I usually make more than 1 move per day, but sometimes it may happen to lose some days or even 1 week.
On IYT you can change your time limit, but only out of a tournament: this is one of the reasons that made the League successful.
I believe a 3-days limit with vacations on may work: the game would be fast enough and you can avoid problems depending on weekend days or holidays.
I think this is a good compromise for the first "gran slam" tournaments.