Grade is not training age. Sort every athlete by structured training history and how they respond to it. Get the right tier, the right program, the right progression rule, and the exact trigger to move them up. Build the depth chart. Print it. Put it on the wall.
An 18-year-old senior who never touched a bar is a novice. Put him with the seniors and you will crush him or bore him. A 15-year-old with two structured years under the bar is past that stage. You do not program a body by the year it was born. You program it by the miles it has under load.
Group by grade and you run one program for four different training ages in the same room. The true novice gets buried under volume he cannot recover from. The kid who is ready for waves keeps grinding the same weight and stalls. Everybody gets the average. Nobody gets what they need.
Everybody starts White. No exceptions, no matter the grade. You earn Silver. You earn Black. Hit the benchmarks, put in the attendance, and you move up. When a kid graduates a tier, make noise about it. The younger guys watch who did it right. Celebration is the engine. We don't do handouts in this sport. You earn what you get.
Your Black-tier athletes are not just the strongest in the room. They set the standard for it. They spot, they cue, they hold the White guys accountable. The room polices itself and your best players own it. High expectations plus high support, built into the depth chart.