Catrick's threads are about the very best
I don't read all the sales threads, but I ALWAYS read Catrick's because I've known him a zillion years...and he's funny. He's a great salespreson too.
I've seen him "bundle" books. He lists the books, describes them, takes pictures and if they don't sell, he puts together a bundle or breaks them up into several for less money. They seem to fly.
So there you have an opportunity to sell some stuff individually for a better price,and blow out what is left over. You'd probably make more money that way.
That way people get a bargain, the seller gets rid of stuff in a group and the customers sees what they are buying.
The main difference is, it's work. Tossing stuff in a box is always going to be easier, that's one of the reasons so many people do mystery boxes on charity threads, for Christmas raffles, etc.
Sometimes they want to surprise people, but overall...taking the time to list stuff is time consuming.