When I was growing up in Ireland it was 6/7 for First Communion, preceded by Reconciliation (called Confession back then) then 11/12 for Confirmation, and it was done through school, with really no option to drop out. The local C of I parish had a similar no dropping out regime. The DCs went to a parish school in the US and First Communion was at 7/8, with Reconciliation at 9/10 and optional but heavily subscribed Confirmation at 13/14 and on. The parish ran a Religious Ed programme and between parish school and public school children the number for Confirmation was about 130 normally. Same for Communion each year.
Preparation was far more intense and involved far more reflection for my DCs for all three sacraments than I recall from my childhood. There was also a significant element of involvement by parents when it came to Communion and Reconciliation, with evening prayer services throughout the year of preparation, an invitation to parents to re-learn and maybe reconsider their own understanding of what they were at. It was up to parents to decide if they thought their child was ready for the preparation. There was absolutely nothing of that nature when I was growing up -- it was all done in school and parents showed up on the day to take pictures.
For my DCs, Communion prep focused on being the family of God and receiving a great gift from God, so a very child oriented theme, placing the sacrament in a context that the children could identify with at their stage of development. Reconciliation prep (again one full year) focused on breakdown of the relationship with God and how to maintain and mend it. When it came to what to wear, the Religious Ed office sent home a note suggesting that attire should be formal but that whatever the family would normally consider formal was acceptable. Nearly all the girls wore some sort of white dress and the boys wore ironed trousers, shirt, tie; some wore a jacket, some wore a jumper. One year, a boy had insisted that he wanted to wear a silver jacket with his navy pants, shirt and tie, and he did.
Both Communion and Reconciliation were prepared for with family members, through homework, meetings in the church and school hall and in the classrooms. Confirmation was a year long course, with monthly meetings held entirely through the parish and involvement by parents confined to nagging to do the homework. No classes were done in school hours. Volunteers from the parish acted as mentors and the children were expected to demonstrate personal commitment and responsibility by clocking up service hours (lots of scope for volunteering in the community), reflecting at length on the gifts of the Holy Spirit, interviewing people (family, neighbours) in association with the reflections, participation at an acceptable level at the monthly discussion/prayer meetings. Clothing for Confirmation ran the gamut from dresses that could be worn clubbing to sober suits for the girls, and heels went from flat to five inches. Boys mostly wore dark suits. I had to wear my school uniform to mine.
Catholics who present their children for baptism are asked to commit to teaching their children about their religion, to bring them up as Catholics. The Church does ask for commitment from parents and eventually from young adults at the time of Confirmation. I think it recognises that exposure to religious education and a Catholic upbringing doesn't always 'take', but it also recognises from centuries of experience that passing on religious beliefs through the family context works a lot of the time.