My son had a speed and agility trainer he loved, went once a week. The guy told him he would be sub-7.0 by senior year. He was an older guy and didn't seem to realize it would have been useful (for recruiting) to get there earlier.
The travel coach kept saying "get his 60 down". I read advice on here and elsewhere. Summer before senior year, we worked really hard on it, especially his start. Videoed him running it (on a football field) and looked at technique. I think I actually looked at PG videos of kids running sub-7.0 and counted their strides, compared them to his (I was kind of crazed). He studied Usain Bolt videos. Finally one day he saw someone instructing another kid at the track, and tried something they said. Suddenly at an August showcase he was running 6.55.
It may have been mental. But some of it is just up to your build and growth. Honestly, I'm not sure whether he could have done it before then. But probably we should have found a track coach sooner.
Ironically, in college he was recruited as a two-way (D3), but became a pitcher-only.