Another thing to consider is if you aren't one of the parents, but want to have access to the child. Like, for example a grandmother.
My mother raised her grandson for years while her daughter was getting her life together. And now she hardly ever gets to see him.
Legally, she does have a right to insist on it, although she doesn't want to rock the boat, I guess. But, if you want to be a part of a child's life and you feel you have a right to that, you should make sure to fill in an affidavit of your own.