All tanks need to have methods adapted to fit that particular tank so it may take some time to see how things fall.
In general, I would think keeping a discus tank as clean as really able is good. From there is can depend on how the tank is set. A bare bottom tank and I would definitely chase every bit of debris I saw as that will reduce my filter cleaning needs. Filters only hide the junk where a siphon actually removes it so I siphon as the easier way when it fits.
A planted tank and dirt bottom will require lots different methods. One with a sand bottom will get less aggressive siphon but just enough to remove the top layer of things drifting around.
I look at siphons and filters as two different ways to get the same job done. They both remove junk so which I really depend on most will be set by which is easier for that specific tank. Some I find it easier to siphon it, some easier to clean the filter but the whole objective is to keep the nitrates and other pollutants down in the easiest way.