I think it's kinda strange that you're saying up to age 19 is "the very limited tutorial area", as if it doesn't count. Up to age 3 or 4, before you have stable memory, perhaps I could understand, but I'm well, well into middle age and I think of some of the time between say 10-19 as the most vivid in terms of my memories, friends, direction of my life, etc.
I have almost no recollection of school except for maybe a couple of dozen moments and a handful - no more than 4 or so - acquaintances. They were friends at the time, but we went to different colleges in different towns, we're not close now.
I remember books I read, but they're detached from a timeline. I remember programming - that was the most formative thing I learned, and it was outside school - but I have very little recollection of actual time spent, just that I did a huge amount of learning.
I'm in my 40s and I remember my school days vividly. I remember like ~20-30 specific lessons and events from 4th grade alone.
In fact when I started a dream diary for a personal experiment, I'm in highschool in most of them - literally, as the dreams take place in the building.
I went through the lucid dreaming rabbit hole when I was 17, I recently found the diary from back then and was curious to see how different the dreams are now.
Myself, I remember maybe one or two things per year from 4+ onwards if I focus; flashes of images. This gradually ramps up after ~12yo, and I can actually say I remember some events from around 16+ well enough to describe them and place in rich context. Properly detailed memory? That starts for me somewhere after 20. I'm 36.
Me too. I think 12-14 is the most vivid for me... I used to enjoy stuff a lot more fully and completely than I seem to be able to nowadays. I miss that.