This was very similar to what we experienced last March. Aside from one out of control wait for the safari we consistently found stand by lines to be 50-60% of the posted wait time. Its almost like they started inflating it to deal with unknowns from genie+? or pushing them up to try to drive up genie+ purchases...
I always think it’s just a matter of luck. We too were there last March, but our experience was the opposite of yours. We waited right around what the posted wait times were pretty much every time (except the last half hour or so of a park being open and during fireworks at MK). I’d say the times we waited 15ish minutes less was equal to the times we waited 15ish minutes longer than posted.
I really didn’t think we’d have to wait as long as we did a lot of times when we’d get in line, but we did. It was what it was though. We weren’t upset over it. I got in line expecting that wait. But at the same time I kind of didn’t haha.