Puck hose carts are very robustly built, and depending upon the hydraulics system on your tractor can reel on a lot of hose at once. The amount of hose one should reel depends upon the care that is taken at couplers.
Reeling couplers onto the cart is where most hose damage occurs. Damage occurs into ways. The first is when the coupler first passes around the center drum, and the hose is coming off the coupler is forced into a sharp 90, causing damage to the hose both inside and out, and often resulting in failure later. Proper practice is to back into the hose at the coupler so that the hose is loose on both sides of the coupler. This will prevent that damage.
The second opportunity for damage is just moments later when we make our first couple of rounds after the coupler. If we reel directly over the hose, or attempt to and have the hose slip across the coupler, the bark may be damaged or cut resulting in future failures.
If great care is taken in reeling around couplers, both backing into them to allow them to be loose on the cart, and then filling in carefully on both sides of the coupler before we reel over the top of it, most hose damage will be prevented.
If you are looking for a rule of thumb on how much hose to pull, we would say 2-3 lengths. Our carts are capable of doing much more, but the more weight we are pulling, the more opportunity we have to damage the hose if we make a mistake at a coupler.