Even if this is right (and I definitely think there is a lot of truth to it!), planning is not the only kind of "writing down ideas to reinforce and flesh them out" activity. Is it the most valuable one? And is this the only and best way to reinforce and flesh out ideas, or are there other ways that might be even better, like creating prototypes or just actively fiddling around with different approaches and possibilities? In my view, it isn't that there is no value in pondering the detailed sequence of work it will require to accomplish something over the next three months, it's more that I think beyond a horizon of a few weeks, most of the other things I could be doing with that time usually ends up seeming more valuable, to me.