I can only answer for the stretches of river that I fish and I've never seen the rotting piles of pellet and boilie that some describe, particularly on some southern rivers.
One particular stretch of the Swale comes to mind when I think about bait quantities and angling pressure. The stretch in mind is now syndicate water, there's a good club stretch just upstream. Back in the day when the syndicate was day ticket it saw a lot of pressure and a lot of bait. It was well known for its barbel, chub and, occasionally, bream, roach and carp.
Now this syndicate are a secretive lot so the full picture may be different. However, I've heard the odd tale of syndicate members complaining that their stretch isn't what it once was and that the club stretch upstream is better. If this is true I can only suggest that it's because there's less bait going into the syndicate stretch than there used to be and the fish have moved up to the heavily fished and baited club stretch. In that instance, more bait in one location would seem to have been beneficial. However, if I'm fishing that club stretch I keep the loose feed to an absolute minimum. They seem quite spooky if greater quantities of bait are encountered.
To my mind too much is somewhat less than the amount of bait that the fish can polish off. The idea of rotting piles of bait is way beyond the pale. However, I suspect that too much for the fella you encountered will be much, much less. He's obviously more concerned about following on from someone that has fed heavily and that affecting his day's fishing. In that case it's hard to say what exactly is too much. I've seen suggestions that a well fed barbel is likely to spend at least a day digesting its meal. If that's the case and you follow a fairly heavy baiter then you aren't going to catch that well fed barbel for a day or two after. The heavy baiter only fed too much if he could have achieved the same effect using less bait. In his defense, he's not to know who or when someone will follow him into the peg.
