But I can make a guess about how his mind works.

So you look at how often you're able to make a guess.

My father might take 10 minutes to make a guess.

No one will ever know, though everyone can make a guess.

You could usually make a good guess as to the time.

And we can make a pretty good guess as to why.

Reading between the lines he could make a pretty good guess at what had happened.

He didn't even have time to make a good guess!

Might you be able to make a guess like that about us?

So I make a guess that perhaps you were involved.