I cannot imagine harvesting without a cart. It seems like it would be very inefficient.
We ran for years with 1 or 2 combines (9600's) and a single tandem truck. Dumped "on-the-go" into the truck so the combines never (rarely) stopped. Not much room for efficiency improvements there!
Then the combines got bigger. We needed 2 tandems going to keep up.
We've run a cart for the last 6 or so years and it is sure hard to beat!
Yes, you can put anybody on a cart, but if you want efficiency, put your best on the cart. A good cart operator gets to see every combine, every corner of the field. He can let you know if you missed a short swath somewhere in the night dust. Can anticipate when/where/what order to unload combines to keep everyone moving.
Our cart is 700+ bus. One night we had 4 machines running in 40 bu canola on a wide open 1/2 section: 9860, 9770, 8010, 9600. He'd grab 2 machines, head for the truck. Grab the other 2, head for the truck. Repeat. That cart never quit moving! I'm still not sure when he found time to eat supper that night???
Andrew