Should buying a foreclosed property always undergo a bidding process or auctioning?

There are some banks that announce the auction date for some of their foreclosed properties. However, if there are no scheduled auction, most banks just let buyers submit their offers and usually within three days, if still there are no other offers, the offer will be decided and be approved immediately if the offer price and documentary requirements are acceptable and complete. However, if during the submission of offer, there are also other offers or offer submitted, it will automatically undergo a sealed bidding process. Buyers can resubmit their improved offers until the last date set up by the bank.