Does every sincere deed reach the deceased, or is a sincere intention alone sufficient for that?

If a person intends to dedicate the reward of his deed to a deceased person, then the intention must be renewed with each new act of worship or deed performed by the donor. The previous intention is not sufficient for the reward of subsequent deeds to reach the deceased. The intention of dedication is necessary for the reward of the deed to reach the deceased, based on the Prophet's (peace and blessings be upon him) saying: "Indeed, actions are by intentions, and every person will have what he intended."