There is always the thought that we may not be done. Several of my friends have had second families, even with the same spouse, after they thought they were done. One actually decided to have more children after their kids were nearly in high school.
I was an accident, my sister was 11 1/2 and my brother turned 15 two days before I was born.
I think that it is often the case where the parents decide they want more kids later on. One friend forced hubby to have a vasectomy because she did not want to get pregnant again. They divorced a few years later due to her suddenly getting baby fever. There were many other issues besides this but it was the one she dwelt on. She could not find a doc that would reverse the vasectomy.
She now has 2 adult children and 2 children in elementary school or middle school. She is happy and fulfilled with her newer hubby and her children.
So my thoughts are that it's always possible. The sudden urge or need to have more children can sometimes be a surprise. My friend who lost her son from a bunk bed accident had 4 more children after that loss.
I know of people who did decide to do permanent birth control and it didn't work somehow. I think if you are going to do it then doing it right is a good thing. The Essure procedure is good because it is testable. They run dye down the tubes and if it gets through it is fixed, if it doesn't go through a person can be pretty sure they won't get pregnant.
Making this decision is personal of course. Having more kids is a joint decision. Talking with each other until you are sure is the best way to go.