OK, seriously, you should put END (or some such markers, -30-, FIN, End of Transmission, etc.). Why? Because without it, the editor/agent/reader would have no idea if there's anything more... especially if the pages got shuffled or the entire thing fell on the ground or something... They need to know if they've reached the last page (if they actually read the whole thing), that it's not somehow cut off.
So this is not done for the writer's benefit or to annoy the writer. It has a practical purpose for the prospective readers.