Running a window AC unit vs central air this summer

My house needs more insulation. It’s coming but it’s almost a 5k job with sealing and other things so need to save up. For now (or if this works well enough, forever) I was thinking of buying a good efficient window unit to run at night in the bedroom. The logic is to use central to keep the house below 75 during the day then turn it off at night and run the AC in the bedroom. I have seen some People here try it out so wanted to check if anyone else has done this.