we always do...those first 2-3 hours as the best. and my kids are early risers no matter how late they stay up..so if they're up might as well hit the parks as soon as possible
and with little kids that's fantastic.
hit all your favs, and then some long before the crowds come, plus be hungry to grab a bit about 11am again before the crowds.
later go to the resort enjoy the pool, then back at the park in the evening for more.
without kids, PM is good but I feel you lose more than you gain, depending on the time of year.
example closing can be 10-11pm with extra magic that's 1-2am. your bound to sleep in the next day, by the time you get up, eat and get to the parks, it could be 12? 1pm even. So you just lost 3 to 4 hours of park time to get 2-3.
but again to each their own. some people are late nighters other early risers.