I’ve just finished replacing all the doors in my condo and another thing to keep in mind is fitting the exact dimensions. If you’re going pre-hung you should have more flexibility, but if you’re keeping the door jambs and just getting new door slabs then you’ll want to measure very precisely. I assumed mine were close enough to standard widths 24”, 30” etc. and they were slightly smaller so I ended up having to trim a quarter inch off the doors to make them fit.