We have two different plans: The June plan (I often go for business) and the fall plan (we've gone the last several years in either September or October). They differ due to crowds and hours, and to a degree the heat (September is summer like, October is not).
When we go in September or October, we take no break whatsoever. We do our lunch PS later (around 2 to 2:30 usually) in an air conditioned facility, and we let that be our break. We also do the indoor, air conditioned rides not according to a "touring plan," but when we need a break. Example: when in Epcot and we're getting hot and tired, we do Universe of Energy, which is almost an hour of sitting and cooling, stem to stern. Finally, if we're up to it, we close the park. If we've had enough late in the day, we leave. This is doable because with the lighter crowds (especially in September), we're able to get so much done we don't feel the need to milk pennies out of our passes.
June is a different story. You'll find a lot of people here take that mid-day break, but this is an odd crowd. I don't mean this in an arrogant way, but when you're in these forums, you're talking to the Disney pros, people who do it over and over again, and when they're not doing it, they're researching, learning, and dreaming. By the time most of us get there, we know exactly what we're walking into, and pretty much what to do and when to do it.
But the average Disney guest doesn't take that mid-day break. When we go in June, my wife and I usually do a 12:30 lunch PS (June 8, Le Cellier, here we come!), then idle out of the park, stopping if anything catches our eye. We'll head to the hotel and catch a swim. Then we'll sit in the room and just cooooool off, maybe even take a lazy mini-nap. We go back about 5 PM.
What we find when we get there is one of the best kept secrets in Disney. It seems there are masses leaving the park about this time, mostly families. I attribute this to many folks who in fact didn't take a break, have burned out, and are heading back to the hotel for food, pool and rest. Many of those left in the park seem slow, cranky, and unwilling to wait in long lines. And a lot of them are eating at that point. Therefore, we've decided the hotter it is, the better the 5-7 PM range is in any park.
There are exceptions to this. MK on a Saturday is always a crapshoot. But even on a Saturday, there is an "attraction lull" between 5-7 PM.
For the most part, that's the plan we follow, and I swear by it. I'll always take the break when it's hot. I feel better, and there are crowd swings to be taken advantage of.
Pat