I have teen-aged boys and a younger girl. They are vastly different in what they need to thrive. All are a mess when their activity/structure needs are not met or are exceeded.

The boys both seem to need structured low-key days with lots of free time. They do best with school and a music lesson each week. That is one hour a week; it is relevant that from the one hour/week there is daily practice plus hours of additional fun play.

My younger DD, however, thrives when she is busy doing things. She needs people and constant physical activity in order to function. It energizes her. Currently she has 8-9 hours/week of scheduled group activities outside of school and she would like more.