Once every two years is more than enough for us. Actually after this trip it will probably be three years before we go back. There's just too many other places we want to go. I adore Disney but I can't imagine spending every vacation there.
We take three vacations a year. One to New England, where I have family. We do something different each time--New Hampshire, the Cape, Newport, train trips to
NYC, etc. One is something local-ish--camping, Cedar Point, Lake Michigan, Amish country, etc. and one is either a big trip (like Disney but as the kids get older we will do so much more . Cruises and the west coast, possibly international if I get brave enough to fly more than two hours, etc) or a second trip to New England. If we go back east again, we try to find new things to do so it doesn't get old. There's so many places to go in that area!
So yeah... We love Disney but our vacation habits don't revolve around it.