If you purchase it prior to 7am (or for the week) it will book that first Lightning Lane for you while you purchase the Individual LL, which is useful. If you are going to stack every 2 hours it's ok to let SS book your next one but you'll have to "file maintenance" it for every 2 hours if you have a specific ride in mind. If you are churning thru the LL's starting at park open, you can tap and go and do it yourself without SS.
