The objective for the AH is to get as much money in bids as possible, not to have an auction drag on.
That said, the 15 minute rule (in my opinion) does not promote more bidding. In fact, it may slow it down. It can be as few as four bids in an hour.
I can't figure out why a 5 minute rule isn't in place for those auctions that close at once. 12 bids an hour sounds better than 4. In fact, I think that over time, that 'rule' should narrow, say 5 minutes until 11pm, then down to 2 minutes until midnight and then every 60 seconds thereafter.
|