In a 2D game where the user moves with the keyboard arrows, should the user send all the time he moves his position (x, y)?. If the user has some speed, the user would send (x, y) like 50 times pixel by pixel in just a second.
Probably you are using sockets. If so, then there is no issue in it. One thing, if your game has physics Angry Bird is type then you should pass relevant info. Like before shooting send positions per frame, after player shoots, then send force, angle, altitude and simulate through this information on other side. If this is not the case then no harm to send info per frame. If data is not very big.