Personally, I have 3 aquariums up and running.
55g - South American Cichlid tank with 4 permanent residents (currently 6 extra babies I'm getting rid of) - When it's just the 2 fish, 1 pleco and 1 catfish I do a 25-30% water change every week, then a deep clean 50% water change once a month, cleaning out the gravel, moving the rocks to get underneath, etc. A deep clean.
35g - 4 Black Neon Tetras, 1 Male Guppy, 1 Angelfish, 1 Twig Catfish, about 15 Mystery Snails - They get a 30-50% water change every week, deep cleaning every other week.
20gL - 3 BABY Axolotls, which I have a substrate that is between sand and gravel... the grains are a little bigger than sand, but they are lighter than grave, so I don't know what kind it really is LOL - They get their poops cleaned out every night, which depletes about 1/2 gallon of water, which I replace. Then I do a 25-50% water change every 2-3 days, cleaning up any pieces and bits that I missed on the nightly clean up.
Whew, all that sounds like a lot of work! lol