That's what I arrived at as well. However, sometimes it's good to make a new plan after a while and then discard that one as well and so one. One could call it "iterative creation of intention".
Exactly. This is also the conclusion I got to. Detailed planning is great in order to tell your mind the direction you want to go to but then it's important to discard it so that you don't get lost in the details or feel frustrated because you are unable to follow every step of it, which may lead to demotivation.