I've played around with hyperedit for a kind of test facility. I don't want to spend 2 hours designing my new Duna rover, launch it only to have it flip or be unable to slow down enough to land. So I would drop the final stage of my rover into Duna orbit around 10 km and see if it can land. If it lands I would then end the flight and launch it for real. Of course this is something I would expect a real Lauch Stuff Into Space-agency to test in some sort of simulator so I don't really think of it as that much cheating.