My brother-in-law does this, they went for 3 weeks this year, stayed in a villa, would get up at a holiday time say 9 am, have breakfast and then head to the parks, sometimes they arrived at lunch time, would moan like hell that the wait times were massive and it was too hot ( we were over there at the same time and it was hot, 36 C most days ) would ride 2 or 3 rides and head back to the pool at the Villa, then they would have a rest day and stay in the Villa

Now we would rope drop at 7.30, get loads of rides done before they had even got in the car, when it got really hot head back to the resort pool or the room for a chill, wait for the afternoon storms to pass and head back in
now for me, the disney tickets are Ł500 ( be that a couple of days tickets from the US price or the UK 14 day ticket ) and its a massive waste just doing the odd day here the there, you pay all that money for the flights, for the park tickets you might aswell hammer it to death, I can rest at home, I dont travel all that way to rest
I know we are all different but its the only way I can ever see us doing it, and as for rest days, you rest on the 8 hr flight over and then the 8 hour fight home, thats enough rest