Actually, that jar guessing game messes up more than just flavor. People forget how much recipes depend on exact textures, not just tastes. Your salt probably wrecked the dough structure before it even hit the oven.
But saying salt wrecks dough structure seems a bit extreme. Have you ever thought that a little extra salt might just make the cookies more interesting? Texture isn't the only thing that matters in baking. I've messed up recipes before and still got something totally fine to eat. Why do we always stick to exact measurements anyway, shouldn't cooking be about trying new things?