Online check-in the day before is for me has mixed results. Some hotels either pre-upgrade you or open OLCI with upgraded rooms available to you. If you see a room you like, particularly if you know the hotel well, then it's one thing less to sort out on the day, particular if you can get the Digital Key to work. And that feature is generally getting better in my experience. When I find myself at a Marriott in particular waiting to check-in I am reminded why I prefer the Hilton family.

The caveat is that in some locations, perhaps a majority, you may get an upgraded room if you check in at about 7 or 8 am on the day of arrival, local time. I haven't totally understood the process, but some local practices seem to keep the better rooms back, and if the hotel is going to be relatively busy they won't necessarily give out an upgraded room the day before. If you know the hotel is going to be full, and the better rooms aren't that special, then you may still want to check-in the day before to at least get something acceptable.

If you don't know the hotel well and if you have particular factors that are relevant in room choice then you best check in on the day, particularly if you aren't arriving late. In that respect it's unfortunate that the App / web check-in does not disclose all room features (e.g. shower versus bath tub, refitted room).

Clearly at Hamptons, Tru, HGI (etc) then typically all rooms are the same anyway so there isn't much reason to wait, other than if (e.g.) you booked a twin room but you'd rather have a king or queen bed.

Mostly I do check-in online, and use the Digital Key, but it may well be on the day of arrival. I almost never change room after that but I know I have that option if necessary.