I don't see a difference between doing 1 park all day with a resort break and doing all the parks 1/2 a day at a time. You still get a morning and evening in every park. If your not a rest in the middle type of person then sure there is an interruption in the day to switch parks and I can see how some don't enjoy that.. i think where your struggling could be you just don't like that method, which is understandable, or your goal isnt' realistic when you get to the park (or you don't have one in the first place). The goal should never be the park, the park is where your goals are, not the goal itself. It's not realistic to experience everything, every time you walk into the park and your trips to the park become the same thing over and over and over again..
From a goals standpoint, what works best for us is we arrive at WDW with a must do, would like to do and don't care about list. The don't care about is probably the best thing we started to make. We know right away what everyone doesn't care about and don't try to fit it in.. We also include places to eat in that. Generally our must dos are the couple would hate to be at disney and not see things. Earlier in the trip it's all about what our must dos are.. Partially this is because some of our must dos are impacted by weather so if we don't get it right away we have other days in the trip to come back and try again. As we go around, we generally get the must dos out of the way, some of the wouldn't minds and experience some things we just forgot about, haven't done in a long time or we just felt in the mood as we were walking past it.
now where it might be helpful is we don't go back in with the same list.. It doesn't mean our favorites will be skipped, but that's not really a goal and it's a if it happens it happens. A lot of our changing parks for 1/2 day is really about mood. we'll get the must dos somewhere done and then the must dos elsewhere start to pull at us. Daydreaming about somewhere else in disney I find takes away from seeing what is around you and why stay in a park when what you want to do is in another park.. We'll go freshen up in the afternoon and now we're in the mood for a different park and head there. If we've been in the park, we probably had somethign we were in the mood for and we'll discuss if there is anything we don't want to miss while in this trip (edit: trip=trip into the park this time). sometimes it's not a specific goal.. "let's go check out things we haven't done in awhile".
Now some other reasons that it works well for us is my daughter has an anxiety disorder and sometimes the stimulation is too much and we just need to go elsewhere after a break somewhere outside the park. Sometimes we walk into a park and realize after walking around for a little while it's just stupid crazy crowded or a really rude crowd.. Instead of having a less productive time in the park and wanted to go all nycer on everyone around us, we head somewhere else and hope it's better (usually is). And last but not least, maybe we're just not in the mood and realize that before we head to a park we had planned to see or after we just got there. We like to be excited, happy and enjoy ourselves.. If we're just in the park like a zombie because "we picked this place 12 months ago" we get out of there and head to where we really want to be....