I have heard those two theories with bidding on ebay.
If you bid early and run the price up, you may scare away some potential bidders and watchers because they see the price as being too expensive. This prevents some people from watching the item and bidding at the last minutes when they get caught up in the moment and bid more then they should. I think this method works if you really want the item and you are willing to pay a high amount of money to get the item. This also prevents you from getting caught up in the moment and over bidding.
The other theory is wait until the last minutes and bid. The reasoning behind this is you keep the price low and you hope that other watchers forget about the item. This method works if you are looking for a deal. The problem is you get caught up in the moment and overbid.
I am sure there are others out there. As a seller, I have seen items jump in the first couple of days and stay there till the end or items that stay low and then go high in the last hour. For me if I want the item, I usually bid my maximum when I first see it and if I don't get it, oh well too bad. If I am looking for the bargin, I will watch and bid the last minute but I always only bid once and don't get caught up in the moment.
It is what you learn, after you know it all, that counts.