The key word here is flip or turn the leaves a few times a day. I have handles as much as 500 pounds of green leaves at a time and if you don't work them, they will sour on you. They can be dried in attics , but you must keep fans circulating the air and you still must turn the leaves.
Another good thing to remember is, keep your daily pick separate from a couple days before pick if possible. Leaves can be a real pain in the rear if you pick enough to make money. My best picking came from a place that several big trees had been dropped. Leaves are easy to get like that. I bought a lot of leaves that came from fellas that got the leaves from places that the trees had been cut.