In sports, no serious coach assumes the original strategy and tactics will survive the entire match unchanged. The plan is necessary, yes  but it must also respond to what is actually happening on the field, not what was imagined in the locker room. The idea is, you must have a game plan that guides your approach but be humble and flexible to understand that, sometimes, the game plan can go to bonkers. In such moments, the best coaches and players know how and even when to adapt, in order to win the game. Victory is the goal, the game plan is just the process. Life works the same way.