Do we need to always reevaluate our thoughts?

That is, based on history of previous events and experiences. And also those events and experiences are sometimes not even ours.

Ok, let me give you a practical example. For example, you once had based your opinion on some subject. Many years have passed, and things have changed, but you still hold the same thought in your head. Do you reevaluate it or not?

Ok, you gave your answer but that's not what I said. You based your opinion in accordance to circustances of the moment. Now after some time the circumstances can change. Do you reevaluate or not?

Ok, I'll give even more extreme case. Someone ask you for an opinion. She/he gives you facts or viewpoint of his/her own. (By the way: Do you make an opinion straight away or do you think for longer before you respond to your friend?) In any case you draw some conclusion given the all parameters at hand.

Now, you completely forget about this question for some time. Time had passed by, something could've changed, but you have your opinion somewhere inside of you. Someone again asks you for your opinon regarding the same question. What do you do? Reevaluate or just shoot out the familiar answer?