Obviously, they are going to test Stealth after a rollback. They don't want to the train to roll back (for many reasons: delaying throughput, customer satisfaction, ride availability etc), so they have to run numerous test runs, to ensure that the launch is working properly. (This is just a guess, I might be wrong). P.S. I'm not one to moan, but could you please check your spelling and grammar next time, so that your posts are easier to read. Thanks .