From my own experience, not really Not for speed anyway. My question for CF was really wanting to know when they had started doing longer SE2 type runs (300-600M)
I find that kids (14yo and under) respond way better to nothing longer than a 150 for Spec. Endurance and 15-20m for speed. That’s how I train my daughters and some other youth athletes. And they keep improving every year while everyone on their old track club is still running the same times from several years ago. My oldest (12yo) can go all the way up to a 800m when she does her pentathalon and all she does is short stuff. Although, she’s pretty active and gets fit from other things.