You don't have to shorten your auction if you don't want to. Its your decision to shorten the days, you don't have to listen to other users, thier plan is to try to make you shorten your auction, so they can win it with thier lowest amonut of credits. GREAT AUCTION!!!
This one user wanted me to shorten my auction, and I noticed when that person won, that person use the lowest amount of credits possible. In other words, they try to trick you by winning your auction with a small amount of credits when you exspected to win more credits.