I have used this feature many times with Hilton. It is particularly useful when you have an international flight arriving at something like 6am. My usual procedure in the past was to reserve the previous night also so that I could go straight to my room no matter when I arrive instead of waiting until some afternoon “check in time”. But sometimes when I didn’t show up by midnight, they would mark me as a no-show. With this new system, I check in the day before, get the key on my phone, and they have no idea if I’m in the room or not. One time the hotel concierge contacted me while I was still at my origin airport to ask if I was happy with the room.