I wouldn't mind getting mail once a week. The question is, would this work for everyone? Are there items that are time critical (need less than two weeks round

I wouldn't mind getting mail once a week. The question is, would this work for everyone? Are there items that are time critical (need less than two weeks round trip) AND must be sent physically AND would be prohibitively expensive to send through private mail services? Considering the items I have in my mail pile right now I can't think of any.