When it comes to durations, you have a wide range of choices: your auction can run for 10, 7, 5 or 3 days, or even only one day if you have a good enough feedback rating.
Theres a reason why you get to choose your duration, and thats because different durations are good for different things. To decide how long you should list your items for, all you need to do is ask yourself a few questions.
Do you want to sell things quickly? If youd rather sell now than in a few days, even if it means losing a little of your profit, then go ahead and choose the shortest duration you can get. If youre the more patient type, on the other hand, you might as well sell slowly.
How much is your item worth? Items with a higher price are worth re-listing every 3 days or so using Buy it Now. The fees arent that big as a percentage of the items cost, and youll sell more when youre constantly higher up in the search results.
Could your item benefit from competitive bidding? Not every item is going to make bidders get excited and try to outbid each other. If you have items that consistently attract more than five bidders, though, you should always list then for as long as...