This is a great thread. I have used some of this material on one of my athletes in his first year of being a 400m sprinter and his first season as a track and field athlete - previously I have coached him as a sprints coach for soccer.
I had do 5 x 200m with 200m jog recovery pre Christmas in 28-29 seconds and run a 54 in only his 2nd 400m race went through 200 in 26 and closed out in 28.5
I had him set out to do 5 x 200 post Christmas in 26-27, 200m walk recovery and with an 8 minute recovery after the 3rd rep. He managed 26, 26, 27, 26 and 30.
We had an aim of 51 at the State Championships, but unfortunately was injured playing indoor soccer.