Not all market is awake and not all coin will pump immediately or will pump when others are pumping. Before one can determine if they want to sell an altcoin, they must know or decide if that coin is a long term profitable coin or a short term because most people make the mistake of selling of a long term coin immediately and holding short term coin which won't gain them much. Besides, if the coin is highly potential, one can keep it for when it will be used as a payment method.