The touring plans all suggest leaving during the heat and crowds of the day. Once AK has evening hours, this will work for all the parks.
The reason it works is because people don't want to get up early on vacation. Hitting a 9 AM rope drop at 8:30 means getting up at 7, or honestly, 6:30.
Who wants to do that on vacation?
So. The average tourist get up at 9 am and hits MK at 11. The difference in crowd size during this two hours? 40,000 after rope drop to 100,000 by 11 and 120,000 on busy days by 1.
So Mr. "I'm not getting up early on vacation" and his family hits MK about 11, waits 60 min in the heat for 1st ride, 75 min (in the heat) for second, uses FP for three more, and 5 rides and 6 hours later, his shirt is soaked through, the kids are a wreck, mom's agitated about dad's short temper, it's danged hot, and I'll be danged if it's not starting to rain! Dad's had enough! Every negative stereotype about Disney, played out.
Bite the bullet, get up early, and ride three rides before the crowds build, use your FPs for three more (and there are plenty of places to get cool indoors, stores ,etc - you aren't waiting in line between FPs), leave, come back at 5 and ride 5-7 more rides as park closes, and you get more done, less crowded, and less hot. And, the 1.5 hour swim and 2 hour nap you took in between refreshed both you and the kids.
Heat (and crowds) can be managed. We take trips year round and don't consider heat (or crowds) a factor in our decision. In fact, we had awesome trips in both June and August of last year. I'm much more likely to hedge to a warmer time to ensure the ability to swim, if I factor temps at all (March instead of January).