Why does the bidding end time extend while I am bidding?

For our online-only auctions, if any bids are received within five minutes prior to a lot closing, the lot time will be extended for an additional five minutes (i.e. the auction you are participating in begins to close at 6:00pm and lot 1 receives a bid at 5:56pm, the end time for lot 1 extends to 6:01pm).  The five-minute extension will continue to be applied until no further bids have been placed.