I have formed an opinion based upon my eBay and GB experience.
If the seller believes that the number of persons who have a good understanding of the item which is for sale, I call it the serious market, (Because both eBay and Gunbroker have attracted a market which includes folks who are anything but serious.) Then it is a good idea to permit the auction to run for a longer time so as to increase the likelihood that a high percentage of the "serious market" will see the listing.
Since Centaures are unique and quite valuable, one might assume that the serious market for a Centaure (The shooters who; a) are familiar with the marque, b) understand why they command a higher price, and c) want one enough to pay the price.) is smaller than the serious market for just a run-of-the-mill cap and ball revolver.
An alternate strategy would be to set the opening price high run the item for only three days but set it to automatically relist until sold. This would be more convenient for the serious market.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson