I use paint pads. Something i learned when painting student bedrooms all Summer and with a team of 10 of us, the ones with the paint pads always finished first compared to a brush. As it happens, i painted a ceiling on Friday with a pad then a brush around the edge. No drips on the carpet either.
We used to have a fixed number of hours per room on Student bedrooms and it weas 16 hours including the glosswork doors and window plus inside 4 wardrobes with another 4 doors. Made a bit up on the hours if we were fast that day. Hourly rate was also good for painting as that was Evening work at 1.5X pay