I do 50% every 1-2 weeks.
Water changes of that size have no effect on nitrifying bacteria. That's what we use water conditioners for.
Having planted tanks, measuring nitrates is useless. I have to add nitrates every second day to keep the plants growing.
There are other things in the water that can't be measured, like hormones, that can seriously stunt your fish. Keep the water changes large and frequent, and you pass by most of the problems people encounter with aquariums.