It's good that you are willing to take the time to have a stable environment, it's a good quality for an aquarist to have.
Well some people will argue that on a cycled tank you want to keep low on water changes to not disturb the system. In truth it seems that the system is helped by larger water changes, as they remove things we can not measure, fish pheromones and toxins we may never know are in the tank. Water changes should have little effect on actual water chemistry, and you are not removing the bacteria, there is no reason that it is a bad thing.
I do "40%" changes on my tank weekly. Reason for the brackets is that I'm usually so carried away in trying to get all the muck out that it ends up being a 50-60% change.
Your water changes are your own decision. You could do 30-40% on an unplanted tank with no noticeable consequences, it's a personal choice really. It's also a light stocking so a smaller amount is doable.
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