it varies based on hotel occupancy and expected arriving guests for the next day.
there have been times i have had late check outs for noon, 1:00, 2:00, 3:00.
it just depends on the date you are checking out.
if you are checking out on a friday or saturday, i don't think you will get more than an hour extension.
many weekends are booked and they need to clean out the rooms asap for the next guests.
i found that checking in on a tuesday, is great for getting a room when you check in at the lobby desk.