Do you believe in the say that you should not say sorry or thankyou in friendship.

Do you believe in the say that you should not say sorry or thankyou in friendship. I really don't believe in this saying as I believe that there might time comes where you make mistake in friendship then it is sure that you have say sorry.

And also if your friend have done something good for you then it is important to be thankful to him or her and obviously then it is good to mention it by saying thank you; and it will make your relation strong.

What is your view in this saying; do you believe in it or you simply don't think that you have to follow it.