I’ve gotten the normal stuff via mail: bills, credit card stuff, DMV, the occasional jury summons. And I’ve also dealt extensively with U.S. immigration, which often requires numerous exchanges via USPS.

And all of these things generally work fine with the assumption that response times will be a couple of days, plus the couple of days in transit.

I can’t say I recall ever encountering mail with a strict deadline very near to when I received it. (Usually the frustration is the opposite: I wish things could move a lot faster than they do.)