In my experience it’s good to have a plan but also know when to change it (which can be very often). For our internal purposes we focus on our vision because that doesn’t change. There are then several ways to execute and the method we choose ends up being the “plan”. But we are constantly iterating. Flexibility is the key because the absolute worst thing in a startup is getting caught in your own bureaucracy. Adapting to changing conditions and assumptions is very important.