I think part of the problem is the information those calendars are based on is outdated. I think so many people now research when the “best” time to go to Disney is, that the formerly “secret” times are well publicized, and thus now overcrowded. We started taking big family trips in 2004 and would always go in the summers. From 2004 – 2011, June through August were PACKED. Then we noticed in 2012, it was suddenly really manageable. Hot and miserable ? Yes. Too crowded to have fun ? No.
We just got back from a trip the week after Thanksgiving, and it was FAR more difficult to plan. Getting good ADRs at premium venues was near impossible, even at 180+7. For example, I wanted to find a Beaches and Cream ADR as we were staying at Boardwalk – best I could do at 180+2 was 8:10 pm. Now, I just checked 180 day today and no problem getting a 4 top there on 8/4 (which used to be impossible). Now rather than rely on crowd calendars, I just follow some basic rules – avoid EMH parks if you’re staying off property, and try to hit MK Sunday through Thursday.