Or alternatively doing less at a time. Can you replace the vanity without doing the floor, then when that is done do the shower, then the toilet/floor. (in most bathrooms the toilet is the only think that needs to sit on the floor, the rest you can shim and then hide the seam in some trim). I try to break all my projects down into things I can do in a day - often not possible, but when it is I'm more likely to get them done.

Then you paint the place several times. Or it looks partly done for a long time.

Paint is quick and easy. Not that I disagree with your point, but it isn't a big deal.