With a planted tank it depends on your dosing regimine.
If you're going to have a low light tank with easy species like swords anubias moss and java ferns and NOT dose any nitrate or phosphate- simply let the plants live off the nitrates and phosphates naturally produced by your fish, and you keep your bioload reasonable you could get away with monthly water changes at the outside.
Once you start going high tech and adding fertilizers water changes become much more important to stay on top of. You really must do them weekly.
I never change less than 50% and I try to do them weekly, sometimes I go 10 day to two weeks. I could probably get away with less in my low bioload low tech tanks, but I don't think its fair to my livestock.
If you heavily stock the tank with fish you'll also have to do them more often.
No matter what- there is no way to duplicate the naturally occurring self sustaining eccosystem in an aquarium. In nature, evaporation is replaced by rainwater, natural minerals from surrounding soil and rocks seep into the water. They are not required to sustain as much life as we require for a tank. The biology is specific and a result of millions of years of evolution to get exactly the right balance of bacteria, insects, plants, algaes, fish etc. They are huge bodies of water leading to much greater stability and have insanely complex food chains and biological relationships we can't possibly hope to recreate in a couple gallons of water indoors.
You can get lucky with being lazy sometimes, but that's not the proper attitude to take when you're talking about keeping living creatures. No offense meant to anyone who disagrees