Opportunity cost for reasoning time

Sometimes I wonder if it takes time to think, and you are deciding between two choices of a way to use your time, then do we have to take thinking time into account? When you use the time to think, you are sacrificing the time that can be used to do something else. Of course, one can calculate the amount of gain that one derives from thinking, but that itself also requires time. So, how much should we think? It seems that economics cannot really answer this question because they assume that humans are rational beings, which implies that anyone takes an infinitesimal amount of time to figure out what is good for him.

In real life that is obviously not the case. It takes some time to come up with any useful thought. A particularly interesting situation arrives where the more time you take to think, the more likely you are to make the correct choice. However, the later you respond, the lower the benefits of making the correct choice. If the function of thinking time to benefits of making the right choice is established, then it would be simple. However, the function differs from situation to situation, and the function itself is by no means easy to find. So, is there any way to figure out how long should we take to think?

Why do we even spend time thinking in the first place? Assuming the hedonistic view, we would be thinking for this amount of time because we find more joy in thinking than actually settling down on one particular uncertain choice. It could also be that the fear of uncertainty hinders us from making a choice as yet. When the time comes such that we are confident enough, i.e., the fear of taking too long to make a choice overcomes the fear of uncertainty, we settle down on a choice.

So ultimately the amount of time spent thinking is based on instinct. Even after thinking, our choice would still be based on confidence, not really reason.