For us it just depends on what we have scheduled that day and also which park we are in/going back to. We usually don't leave a park till after lunch, but before 2pm. Then we are back in the park in time for dinner. On average I would say we are typically leaving a park around 1, and are back in a park anytime between 5 and 7. It can take up to an hour to get back to our resort on Disney transportation, then a few hours to swim and freshen up/change for dinner, then another hour to get back to the park. Our breaks are usually no less than 4 hours total. In the cooler months we take less breaks since it's not so hot midday and the parks close earlier at night. But in the summer when it's hot as hell midday and the parks have decent late hours we take breaks everyday.
Some people find breaks a waste of valuable park time. For my family these breaks make our trips so much more enjoyable. Not only do we not get burned out on the parks, or over tired, but we truly enjoy hanging out at our resort pool midday. In the "early" days when we did the parks commando, we came home from those trips absolutely exhausted. When we started incorporating daily breaks (especially during the summer) we enjoyed those trips so much more. Those trips actually felt like a vacation and we weren't exhausted at the end of the week.