Yep, just did it yesterday. Though oddly I tried to do it the night before and the automated system was unable to process payments at that time. So when it works, easy and painless. When it doesn't, not, LOL
So moral of story, don't wait till too close to the trip
You don't have a credit card on file.
You have a credit card on file but want to pay off balance with a different card or gift cards.
You have a room only booked and want to make payments every so often as to not have a large balance upon arrival.