I've always mixed things up considerably- how often, how long, overall budget. So my answer is kind of neither. Maybe skip WDW for a year, maybe take three weekend length trips. about the only thing I don't do is go for more than about seven days.
This year we opted out of the extended-family trip. The new WDW dynamic changes things in ways that don't work well with my extended family.
I know enough of pricing WDW visits to know a good deal (air, hotel, tickets) when I see one.
I actually like mixing things up. I don't relish being locked into taking a trip of a certain length, or staying at a certain place.
Your question also assumes that time is not an issue. It's too much to take off 14 days all at once! So how much time we can spare is another factor. Sometimes three days is all we have!
Last, seven is great amount of time in WDW, after about seven, the crowds/lines/same songs/big meals over and over start to get annoying.