Yep! This is exactly what I do. I win 97% of my auctions this way - and at the price I want.

The 3 percent that I lose is because I wasn't willing to bid higher than another person at the end. Once, when I still had dial up, someone with DSL got in a last second higher bid over me.
There is something called "Emotional bidding." If you bid too early on an auction, others see the bid & try to outbid you. When they place a bid & the eBay computer puts in your proxy bid that outbids them, they may emotionally start entering higher bids just to outbid your bid. This UNNECESSARILY jacks up the price that would have otherwise stayed lower, had you waited til the last few seconds to bid.
You see this on auctions of products with multiple listings. All the items are exactly the same, some may even be listed by the same Seller, so there is no difference in the auctions or items or Sellers. But people start bidding on the same ONE auction, driving the price up, while no one bids on the other auctions.