The first need for the success of any plan is to decide what it is you have to counter.
For example an athlete planning to enter professional sports must first counter their physical limitations. They do this by practice to get better at their chosen sport, and exercise to increase stamina, endurance and muscle mass. A business might have to counter a marketing campaign by a competitor, and a politician or entertainer might have to counter negative reviews, news and opinion articles.
You create a plan as your roadmap to success, and as a roadmap it must have directions. A plan cannot be considered complete if problems met along the way have not been recognized, imagined, and made ready for.
Meeting a problem then having to back away from it, stop, then say,
“Wow, what do we do about this now? We never prepared for this. There is nothing we can do about it because we never thought it would happen, so we never considered a solution for it.” might derail any chance at success you might have.