Yeah, the picture in the comment is still small scale, but illustrated what I'm talking about.

So the bottom row, a guy standing on the ground does.

That second row, would have a guy standing on it. He do his feet, the row chest height, and then usually one more row above. Then another guy on top of that is as high as we'd go. So the higher up you are, the less you have to lift, but the scarier it gets.

I remembered the ones I visited in Cuba were 10 feet high tops

My uncle that fell out of a barn started using crazy long rows one high, and then he'd put tarps over it so it doesn't get rained on.

It's just takes up an insane amount of space, and the curing (drying process) isn't as easily controlled, the plants on the end will all be lower grade. It's sold via auction, so pennies a pound adds up.

In a barn there's going to be narrow doors on the side that go up the whole length of the barn, every 10-20 feet.

Depending on conditions you open/close the doors to slow/speed the process. The better it goes the more you make when you sell.

Same principle as why you keep cigars in a humidor