Newborn long sleeve sleepsuit

Hi mummies, FTM here. Are long sleeve sleepsuit important for newborns? In what situation is it always used? Is it only when using aircon? I currently only have 4 pieces of it, 0-3M, 3 pieces 3-6M, will it be enough? As i scared buy too many end up not using. #firsttimemom #advicepls