Do you ever mow tall grass ?
Running the mower over your own clippings is the fastest way to overwhelm a deck .
Back in the days before catchers we used to mow a small patch in the middle of the lawn then go to the edges & mow clockwise so all of the clippings would eventually end up in a pile on the section you originally mowed.
After you carted the clippings away you then had to go & recut the last 1/2 to 1/3 because the volume of clippings being shoved around prevented the blades from cutting all of the grass .
The best mowers for rough cutting are the flail mowers that are rear discharge, sort of like a cross between a reel mower & a tiller on steroids.
Second best are the rear discharge with counter rotating blades