It's not uncommon to do that when you are doing a proper job, to make sure the paint matches. If you eg have a damaged door and just repaint the door and don't do the surrounding panels, any slight mismatch in colour can be very obvious, especially in bright sunlight. The need to find suitable places on the car to 'lose' the edges of the respray usually means respraying an area much larger than the actual repair.
- HZ