It's not an excuse not to have a plan. Strategy is dynamic and iterative.
When you get punched in the mouth, you just adjust your plan based on new evidence, you don't throw it out the window.
Besides, business and engineering are not like fights and battles. Sudden shocks are rare and split-second decisions are not often called for. In most cases new evidence comes gradually, there is time to validate it, digest it and re-tune expectations and strategy.
Furthermore, always acting on the main immediate priority/bottleneck rarely leads to optimal speed. In computer science, this is called a greedy algorithm. They are indeed simpler to implement and tune (and to execute by teams), but rarely optimal. Real speed requires making predictions and adjusting them as more information becomes available, this is what planning is.