Here’s the thing, when I was growing up, I lived in the Diocese of Saginaw, MI. Most Rev. Ken Untenner was bishop. Right when I was going to make my Confirmation in high school, he decided to move Confirmation back to being before Eucharist. As such, all children who were either preparing for or had already made their First Communions were to make their Confirmations at the same time. Because of this, my brother and sister both made their Confirmations at the same time that I did. Later, Bishop Untenner died, and the bishop who followed him noticed that, throughout the diocese, parents were no longer taking their children to religious education classes after First Communion/Confirmation. I don’t know what he did, but I read in the bulletin when I was visiting my parents many years ago, that he was contemplating moving it back to High School due to the attrition rate.
Currently, I live in the Archdiocese of Santa Fe, NM, and I volunteer as a catechist once a week. What I’ve noticed is that often (but not always), parents will bring their children to classes until the children have completed their First Communions, and then often not bring them back until Confirmation classes in High School, if at all. Most of the students who come to classes between First Communion and High School come either because their parents want them to come (especially in later elementary school) or because they, themselves, want to come (mainly in Middle School). Even so, not many children come to classes between First Communion and Confirmation. In fact, only a small portion of the children who did their First Communions end up coming back at all for Confirmation in High School.
The problem is, honestly, that we have a large percentage of parents who are not well-versed in their faith. I don’t blame the parents for this - they weren’t taught the faith well themselves. And this goes back, unfortunately, for generations. For a long time, we, in the Church, assumed that “the people” couldn’t truly understand their faith, so we had people “memorize” their faith. Unfortunately, most people didn’t go beyond the basic memorization of the Church’s beliefs, and thus didn’t have a deep understanding of the Church’s reasoning. When the rebellion of the 1960s began, it, plus the confusion of early post-Vatican II years, had people questioning authority in all forms. And this led to some “throwing out the baby with the bathwater”, not realizing that the Church’s teachings could not change.