In fact, if you should fill a TM28 each time you "change your address" that implies EVERY FARANG should fill it EVERY TIME they stay in a hotel. That's absolutely undoable.
Just for additional info about Chiang Mai, where they enforce TM30 updates as well. When I went to update after an abroad trip I asked the officer about when to update. They said "every time you stay overnight in any other province or abroad".
Last Monday I came to pick up my residence certificate at 6:50pm, the office was still open.
There're no people thought, so I think they stop servicing at 4:30pm as usual, but office remains open until 7om or more while doing their work. So not sure if you can update your TM30 after 4:30pm, but for sure office is open.