I can not decide. When I do 10 day auctions I time them to take place over 2 weekends, thereby getting more viewers during the peak shopping time (saturday/sunday). ----- BUT most people don't bid until the last few hours anyway, so I doubt the 10-day final price is any higher than a 7-day final price.
What do you think?
Maybe 10 day auctions are best for rare items when there's no other sellers to compete against.