Good point, Tom. I do a water change of approx. 50% twice a year, spring and fall cleanups.
There are a lot of factors that go into how often you need it. Heavy plant load will absorb nitrates. Few fish or no plant dosing will also preserve water quality. But lots of fish and few plants will create excess waste and poor water quality. But your 50% changes is probably right on. Better to be aggressive than change too little.
