When touch up paint is needed
Painting Tip: Here is something I like to do when I paint a room for a client - when reinstalling the light switch plates to the wall, I put a piece of tape on the inside of the plate (connected to the wall that has just been painted) and write the paint name, color and number on it, for future reference.
Often times down the road touch up paint is needed. This ensures my client will never forget what colors were used in a room. Huge help!