When should a decision be fast, or slow?

I read a book about military strategy... I forget the author, but it was a US General shortly after WWII.

He stressed how he realized that you should make a final decision as late as possible, and no later. That is, be prepared to immediately decide as soon as the question is upon you, and delaying would be harmful; but so long as you can delay the decision without consequence, you should delay.

The "prepared" part seems like good advice because many decisions can be made in advance, only contingent on future information. You might not be able to decide far in advance what exactly to do, but you might be able to decide what to do if X or Y happens, and what to do otherwise. Then when the moment comes and X happens, you can decide fast.

The article talks a bit about imperfect information, which does throw a bit of a wrench in this, so it doesn't apply to every situation.

A decision should be fast when it is needed urgently or if the person making the decision is confident about all possible outcomes. And if not it's best to take one's time(slow)

I rad in a book that fast thinkers is best. So decisions should be fast

You might consider some skepticism towards one-size-fits-all solutions.