Depends... are you asking specifically about WDW & DLR...? Or do cruises count? I'm in Oregon - it is MUCH more affordable for us to bop down to California vs. WDW as far as airfare and hotels go.
If just the parks, I went to DLR yearly as a kid then went on hiatus from about 2000-2008 while I was in college and getting my career together. At the time my father was bored to TEARS at doing it every year but it was what my mother wanted. I really laid it on thick too - I loved going right before the school year started and by the time I was a month or two into summer and properly bored I started begging him too. Poor man didn't have a chance..!
In 2008 I went to WDW for the first time with my brother, then started visiting every 18 months or so, sometimes with my boyfriend (now husband). He thought it was too often to be honest even though some of those were with my parents instead.
My husband got me started on running 5Ks in 2010 which turned into half marathons so we were averaging 2-3x a year between both coasts due to races (only partly an excuse..!) There were two years that it made financial sense for me to get the Premier Passport since we were going so much..! I think the most I did was 2x to WDW and 2x to DLR in the same AP period. I did not get bored. My husband wondered if he made a mistake...

I tried to make one solo trip, but he ended up joining me for half of it at the last minute. Sadly I think going so often is off the table for me now - he just doesn't like me running off alone even though the heat and rush really gets to him quickly. Plus...
..my husband broke his toe back in Aug 2014 which sadly put a stop to races. We actually went three times last year (2x weekend trips to DLR and 1x to WDW) but only did WDW since I won a trip, and one of the DLR visits was to use up an airline refund that was going to expire. This year we are only going to WDW for a long Food & Wine weekend (his favorite and I like it too). My husband is still having toe issues but he REALLY wanted to do the DLR half, but there is so much under construction as well that we gritted our teeth and are staying away from it for 2016.
I honestly am not sure how much that adds up to, lol! There are cruises and trips to Euro Disney and Tokyo
Disneyland & Sea in there as well.
Personally, I have found that is long as we also do other things then it works out great to go every year or so for each park. The years we were doing races and blowing our vacation budget on only Disney were really grating to my husband. My Dad's main argument when I was a kid was that we were going to Disney at the expense of everything else. It was ALWAYS a week at the beach and a week at DLR. He wanted to see other stuff too but my Mom would never agree. Now, last year even though we went 3x to parks we did a bunch of other trips too - one of the DLR trips included stops in San Fransisco & San Deigo, we also stopped at some wineries in Glen Ellen on the way home. We went to Europe in September, tried an RCCL cruise, and I think it has made all the difference. He is excited to go back to WDW in September even though we were "just" there is October and is really excited to get back on
DCL in May now that we were just on RCCL. Variety is the spice of life, even if Disney is one of my favorites!
