It worked because in a way, they already had it in them. They both were (and still are) very curious and self-starters. They liked unschooling for a while, and to this day they still have an do-it-yourself attitude when it comes to learning things that they’re interested in —- I think most kids do, and in their case it got cemented during this period.
But they got sick of it too, they got sick of not having a clear schedule, clear goals to meet, too much uncertainty. Now they like more academic-oriented schooling, a bit of the opposite of unschooling, and they’re thriving.
We were lucky that the director of the elementary school they ended up in. She was very welcoming of our kids, and expressed that she herself had an unstructured upbringing. More interestingly, she seemed to think kids should have some unschooling period in their lives, as having free range helps them develop as people.
Anyway, as I said, 2 data points