We did Jersey Week in '00 with my Monmouth County sister and her family, and are doing so again this year. She had done Jersey week in '98 as well. In '00 there were a couple lines that took some time, nothing outrageous, and some that you could get off, and go around and do again sometimes. But NJ sister told me she found the crowds somewhat larger that year than in '98. SuperSoap was getting underway as we were there, and the Food & Wine Festival was a fun afternoon. The weather was slightly too cold for swimming that week, but comfortable for getting around the parks and not getting overheated. And the low to mid 70's temps didn't stop my "norhtern" nieces and nephews from wanting to swim. There was also a warm enough day at Mickey's toon town that the kids decided to get splashed around there on whatever that water attraction for kids is at that area of Magic Kingdom.
Jersey week is not a myth, but it is verry do-able, but not peak water-park time to be counted on.