It may be common sence but i bet not everyone thought about it so when you are trying to sell something which is not selling but you dont want to reduce the item cost for buyout simply remove auction and put it again into AH tab.
This works because many players only check Auctions which have 1d + for regular items and 1d 10h+ for sniping as they expect if item have less time it shoud not be good so you might try to replace the item in AH sometimes insted of waiting 1d 12h till it becomes unsold as most items with less than 12h are not going to sell anyway.