This is a very good question, getting a feel before painting starts. A professional paint proposal should have this estimated. Reason why important, in both extremes. On first day, 1 painters shows up, painting your entire interior or exterior, don't care how fast they may be, will take that one person 6-8 times as long than having a team of painters. On the flip-side, having an unusual large number inside or outside your home can be just as bad. Reason getting a job done too quick, is quality control standards seem to suffer. When a job normally takes 3-4 days with 3-4 painters, but is completed by 12 in one day, look out. Unless an interior or exterior job only needs one paint, same sheen, same color for everything, with very little caulking, masking, it can be done. Typically quicker jobs done in new construction, not repaints. No other important point as important to another is having the correct number of painters on your job. Taking a paint job from beginning to end, in the most reasonable time possible. Your painting contractor should know exactly how many painters to staff your exact needs, being a very good question to ask.