How Much Planning Goes Into Your Gameplay?

I like a story, from planning the characters and what life was to what will be shown or revealed later to even just adding tiny bits as things go, sometimes I can just play and mess around for nothing but having a little more is what makes things different. As yes some things are repetitive but that's how life is too, everyone has things they do that might happen in another family but the background is what matters for that. So half and half planning and nonsense with eventual stories keeps me going even if I take a while to get to things.