We had it for the maximum period of 6 days because we were in Paris for a week. You don't save a ton of money, but just booking the time slots makes things a lot easier when you get there. The week was planned out in advance, but there's no other way if you want to see/experience something. Queuing up on site is usually pointless because it's very busy in July and August. We always had two activities a day, except for Versailles. You need a whole day for that. Everything worked out great...but you should definitely book a time slot wherever possible. The times were always kept to and we got everywhere on time. I would do it again anytime.