I have a new appreciation of carts. Prior to iron and reinforced 24-slot boxes, you are limited to 10-slot boxes. Carts have 18 slots.
Dump boxes are boxes you put near a portal so that when you are in the field and either have full inventory or are at your weight limit, you port home, and rapidly dump everything into a dump box, then go back out.
18 slots matters because the whole point of a dump box is to stack things. If you sort things into your long term storage each and every return trip from the field, that is a lot of trips for partial stacks. When you use a dump box, you make full stacks and fewer trips to long term storage, which means more time stabbing boars. A 10-slot box can only handle 10 kinds of items, and you have to go across multiple boxes to dump a typical inventory from the field. The cart however with 18 slots has enough to dump everything you find typically, and properly stack it. The 24-slot box you get later is even better.
Another great time saver is to craft a cart at your mining site. Put a portal next to it, and maybe a stake wall around it so nothing beats on it and the portal. As you mine and fill up with ore and rock, dump it to the cart. When it gets dark and it is time to go home, take all from the cart, dump back the ore, and encumbrance portal home. When the lode is beat, just roll the ore-filled cart down the path towards home or your ship.
You can wear your cart as you make a cart path, and fill it up without stopping as you go from A to B. It is easy to dodge roll out of it to fight enemies.
Carts are also one of the best ways to transport silver from the mountain to the sea. Built your cart on a wooden plank stretching out over the cliff's edge, fill it with silver ore, and shove it off the plank to the flatlands below near where your ship is. If it breaks up, you can still find the crates. Otherwise repair it and continue down your cart path to the boat. You can encumbrance load and jump off the cliff, but this is risky as your stamina drains out, and if you do not make it you need to build a bench and box to hold all of what you carry, or just spam dump it to the ground. Either way you are at risk during this process.
Prior to long ships, you can increase your Karve's carrying capacity with a cart. There is risk though. High seas can mean the cart either damages the boat or goes over. You can put the handles around the mast to limit its movement, and some claim if you upend it on the boat, it is stable, but still usable.
Most of this other stuff people have posted before, but I had not really seen anyone discussing dump boxes and how carts are great for that.