It's all subjective.
I've read stories of people who stay a week and love it.
But I think it's too long. I find after 3 or 4 days, I'm ready to go home and the park life starts to play with my head.
Agree that if you arrive early, you can do each park in a few hours, leave when it gets hot, then come back at night. Most plan on 3 days at USF/IOA with the idea of visiting a park each day, and then favorites on the 3rd.
You can add DC/SWF if you want more parks to visit. And if you want to drive the 75 miles, you can visit BGT. SWF also has a shuttle that goes over to BGT. You can also add WnW as a water park. So now you've got 6 possible parks to pick from, and none of them are Disney.