I'm not really understanding the saturation view and that hard to come by items are too readily obtained with more auctions ... thus lowering values.
You're dealing with a fixed commodity ... in regard to authentic, original petroliana ... they're not making any more of it. Doesn't matter how many times it's sold ... there is a finite amount of items ... so I really don't care how many auctions or how often something changes hands.
The issue moving forward long term is a sustainable group of collectors willing to buy.