My understanding is that a stable tank supports X amount of bacteria. If you have 1 litre of media, 2 litres or 10 litres, you will still only have X amount of bacteria because this is the amount needed to process the waste from the tank. So it isn't possible to have too much filter media, but the more you have, the more sparsely populated it will be with bacteria and so this space could have been better used for other purposes (sponges, filter wool, Purigen, etc). Having additional media does of course give room for the bacteria colony to grow if needed to cope with higher waste levels (e.g. fish stock increased).
Also not all media is equal in terms of bacteria housing capacity so you might need 5 litres of plastic bio-balls to do the same job as 0.5 litre of Matrix, or something like that. And not all bacteria live in the filter either; a significant portion might be inside the tank in the substrate etc.
Worth checking the manufacturers recommendations on the packaging. 1 litre of Seachem Matrix is apparently good for an 800 litre aquarium (but I probably put more than 1/4 litre in each of my 11 litre tanks!).
If you have stable zero ammonia and nitrite levels in the tank after it is fully cycled then I assume that means you must have sufficient bacteria and hence sufficient bio-media.
If it's a new tank setup, then checking whether a certain amount of added ammonia (say 2ppm, depending upon your intended fish load) is processed within a certain time frame (say 24 hours?) is a good way to check that both the cycling is complete and that there is a good enough size of bacterial colony.
I usually work backwards when planning my filter: first work out what sponges, filter wool and space for Purigen / charcoal / etc I need, then fill all remaining space with decent bio-media.
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