I wouldn’t necessarily go by age alone. Competitive experience and skill level, (as it relates to current top end speed), are huge factors.
If I am 28 but have underdeveloped top end speed, then I would have to rely on SE to get me thru a 100 as well.
If your athletes are males running 11 sec or thereabouts, I wouldn’t necessarily qualify them as top-shelf HS sprinters anyways. There is a good chance that they are hitting their top end around the 30-35m mark or so. THis is further validation that they need more reps involving top end speed. Rehearsing this skill (flys) provides race modeling and opportunity to work on the technical aspect as well as execution without the anxieties associated with being in an actual competition.