Growing discus and also properly growing any other fish requires daily multiple feedings with daily maintenance in order to optimise good growth and good health.
Once they are grown , you can set back your routine a bit , but you still have to stay diligent on order to keep the discus heathy.
After my discus grew I change 3 times a week 70% water and feed them only once to twice daily with dry foods as a staple .
I change this much simply because my discus tells me so . Just listen to them and you will know whether you are on the right track . if I cut back from the WCs a bit they start to show fin rot , pimples , sratcing or darting, less activity , less appetite etc.etc.
So my advice to optimise your WC routine for the grown discus is to start with more or the most , and gradually experiment with less and less until you find your perfect routine . Once you experience troubles along the way , go back to more / the most , and start again .
Hope this doesn't sounded much confusing
P.S And don't worry about the nature filtration system , its in Gods hands , and he is much more experienced than us here on SD