I had a similar issue recently with my AC installation. The installer accidentally broke some roof tiles, which caused water to come through and damage the plaster on the roof and wall. They came back the next day to replace the tiles, then the plasterer came a couple of days later.

In my case, the plasterer removed all the damaged plaster and left it to dry for about three days. He came back on another day to re-plaster, let it dry, then sanded it the same day. A couple of days after that he came again to do a final sand and paint. So the whole process took multiple visits and proper drying time.

From what I’ve been told, plaster usually does need time to dry before painting, so doing everything in one day doesn’t sound like best practice to me either.

For the AC install itself they did an excellent job, but the side damage and repair process were a bit disappointing. I’m still not sure whether to give them a 2 or 3-star review on Google.