I've seen a guy down at Buffalo Grove, IL. with a cart with 3 bins of tupperware full of discs.
had to be carrying at least 60 discs. it's a wide open 9 hole course with the longest hole around 420 feet. He was throwing 5-10 discs a drive, most of which were r-pro bosses. Tons of bad throws, at least 9/10 and he was cursing, blaming the wind, or the degree of hyzer every throw.
Our group of 3 just sat and watched, as he didn't allow us or the group who was behind us (that went ahead of us and him) go ahead of him. Like he loved the attention to his bad throws.
That was my only experience with a disc cart, and apparantly he's a regular at that course.