A trading plan is basically a set of goals, rules and checklists that you establish for your trading venture. Your plan will be different at different stages of your development as a trader. It will evolve over time and change considerably as you learn more and gain more experience.
To me it is a general guide. I don’t subscribe to stoically “trading your plan” because that prevents you from evolving and improving your plan. I no longer have a written plan since my goals are now set, having changed from learning how to trade to accumulating pips to now increasing my % gains. Similarly, my risk and trade management rules have evolved and stabilized. I have internalized them and don’t need to read a plan to follow them. Occasionally, based on observation or insight, I might tweak a rule here and there. But, that is a mental exercise, a sort of “note to self” rather than pen to paper. I haven’t done that in a long time now.
I believe that creating a written plan comes from the old school of thought where it was thought that formalizing a detailed plan helped things to progress in a predictable manner. That has been shown to be fallacious since nothing is predictable. Agile and malleable frameworks have replaced process oriented methodologies that were previously created in stone and followed with rigor. These frameworks allow you to manage chaos better and to change direction as needed without having to traverse down an unfruitful path for too long just because a plan calls for it.
Putting your thoughts down on paper, succinctly in point form, as you learn might be a good thing as you can revisit them at a later time to refresh your memory, but I wouldn’t call that a plan.
Having created a detailed plan as a newbie I have learned that my time would have been better spent concentrating on developing my trading skills and not wasting time developing a detailed plan. Other traders may share a different view point.