People tend to cling too tightly to plans.

People cling to plans for two reasons:

1) they are a comfort blanket of certainty.

2) They help coordinate across a large organization as a schelling point so everyone doesn't. have to continually relitigate everything.

However, detailed plans, especially in dynamic environments, are brittle and can be big liabilities!

They are extremely expensive to create and change, and also they are based on whatever naive thing you thought in the past.

It's hard to incorporate new things you've learned since you created the plan.

The more details that are pinned down in your plan, the more likely they are to be partially disconfirmed by new information, and the harder they will be to change when they are.

That's why it's better to have flexible plans without too much detail.