LOL I've never done this or even thought about doing it. I now have 6 litterboxes to clean so sometimes after one is cleaned then one of the cats will use that litterbox. I just wait until they're finished and then I scoop. Sometimes I make them get out before they've covered up their business and if I'm in a hurry I'll just wait to clean it until the next time.

Some of mine also do what Donna's cat Sasha does. When I get home they'll run to the litterbox to do their business. Usually Starr and Pearl will do this.