We typically do 8 hours. And always do some ride multiple times. Best thing about the tours is you pay for what you use w/no commitments other then the 7 hours. If you want to extend for an additional hour or more they just charge you afterwards. It’s very flexible. Our first tour we went during Christmas break, super crowded, mine train was still a 3 hour standby wait, we did that 2xs, plus the majority of other FP rides in MK, as well as the other 3 parks in about 8 1/2hours. Unless your planning a sit down meal or extended breaks, book 7 or 8 and then go from there. Everyone is different but if you basically go from one ride to the next, I think you’ll have plenty of time. Remember a lot of time when at Disney is getting from one park to another using the common means of transport. You have your own driver/car and the travel time is minimal. Eg. For Epcot Soaring, you park on that side of the park, do the ride, get into the car, drive to the other side of the park and do Test track. It’s pretty cool how much walking is saved, which means time riding rides! Also remember if there is no fast pass, the tour can’t skip the line so do those rides on your own time. We think seeing the parades are worth the time, not having to camp out of a good spot. You can also ask then to go get you snacks while you watch the parade. My girls always ask for a funnel cake, since the vip seating for the MK parade is close to Sleepy hallow.