Do the community parks ever *actually* change?

The last time I played was about 4 weeks ago, and I remember checking out all 3 of the community parks and thinking they were pretty cool. Today I decided to get on for a few minutes to kill time, and the exact same 3 parks were still there! Is there some feature I'm unaware of? Do they rotate and I just so happened to log back in when the same parks were there? I was under the assumption they changed every 24hrs (there's literally a timer).