1. Film starts at meets, nothing you do in practice can simulate a meet, not even close. Take what the film shows about meet starts and work on corrections in practice.
2. film mechanics at practice and meets. Bad mechanics happen everywhere.
3. you are producing 400/800m runners with these workouts, not 100/400m sprinters or jumpers. I know I've produced a ton of these kids with less work than you do with your sprinters.
4. you shouldn't spend any part of a HS track season building a base, there is not enough time. If they played Basketball or wrestled, they already have a base, now is the time to get them into track shape (fast). If they didn't play a sport or keep in shape that is their fault. If you want your kids to have a base it has be done from the fall thru jan.
5. Every practice session should have a common theme, ie accel (0-50m), speed (30-80m), speed end (80-150), special end I (150-300), special end II (300-600) or general endurance such as tempo or general strength. In season speed always comes first, then you work on event specific endurance, while maintaining speed/accel development.
6. Blocks are the last thing I introduce in accel development, except maybe with simulated start jumps where we explode from blocks to dive prone onto HJ mat. Even then most of my block work is done at 90% because I want good repetitions done each time. At meets I cue them with explode, push, push, push. Later in the season I will 60 and 80m from blocks @95-100% and have them cue themselves. I make sure they understand that I and they want don't quick feet at the start, but higher force production, I can actually emphasize that when I start them with accel drills without blocks that make them react with a high force production over quicker feet. The quick feet part is the sprint stride phase.