It really depends on the auction. Some auctions, I've seen people buy out right away. There are also ones where the OP ends the auction early because of time or lack of interest. Others, last the whole time.
That depends on the person. Shiro's style, isn't for everyone. Just like anything in life, some people like it, others hate it.
Just as there's people who like her work, but would rather not pay that much for it. With auctions, unless you're lucky, people tend to pay a lot more than if the person offered the same thing in a shop.
And I've personally noticed that prices are also seem to go higher faster if the artist is relatively known in TBT. Shiro is one of those people.
I've seen art auctions where the art was really good too, but they barely got bids since not as many people knew them.
That aside, a bidding war is a gold mine for the one holding the auction. The price skyrocketed because some people really wanted her art. Otherwise, I doubt that it would have gotten this high without the bidding war.