I put my max bid in early and forget it. The only reason is i simply cannot stay up late for some of these auctions to end..
I think most of the bidders who bid late are simply enjoying the excitement of the auction.. Perhaps they have their eyes on more than one item but know tehy can only afford one or the other so they wait to see which they have a more realisitc shot at!!!! They don't bid early for fear of showing their hand in a poker game.. IMO..
FWIW, I wish I could stay up late and enjoy these auctions but know that I am probably better off financially because of it.. or perhaps not.