Once you see the lines, you'll have no complaints that the parks close at 6pm or 7pm - because you will be exhausted from riding so much.
On those "off-season" days when the parks close at 6pm or 7pm, the lines are extremely short and you will be able to experience more, ride more, and then ride again versus those Summertime days the parks are open until 10pm (or during the holiday periods).
Honestly, the parks should actually charge MORE on those days when there are little to no lines throughout the parks - it's a pleasure having so much elbow room and being able to ride as much as you want