Oh man, you were doing a titanic work doing them one by one.
I do the same as you discovered. Although unfortunately most probably do the same and that pushes the price down, because Load doesn't just add the lowest price, but actually puts that price MINUS a small amount, to put the card on top of the rental offers (for that card, at that level). The more often that happens (and by many people), the quicker the price drops.
That is actually the only negative point about all this tool. If everything is doing that, prices are simply coming down automatically and they stay there if we don't cancell our contracts from time to time to restart things.