Let me make 1 point perfectly clear, you are correct to some extent, but if you time HS 800m champs in the open 200 you will find that they are as fast as the finalists in the open 200 race. Regardless of the demands of the race. You really ought to do a study on this. However, it gives you something to work from, if you don’t run 200’s in 25 seconds as a HS boy breaking a 2:00 800m will be virtually impossible. In fact if you have 800 champion aspirations you better be able to do someting in the low 22’s.
The physiological demands of the 200 and 800 as close to each as those of 800 and 1600.
How to train use the TP guidelines is what matters. First is reach your TP for 400 and come within 3 seconds of your 800TP. Then you train for speed to change your TP, then you train to reach your new TP and the cycle repeats. This allows you maximize both speed and endurance training. Once your endurance has reached a point where you can endure maximal workouts you can stop most of your strictly endurance in favor of heavy speed endurance and conditioning work.
You cannot go directly from a good 200m runner to WC 800 overnight. That is why you have to go through these periods of cycling. When it comes to track speed matters when you have the guts to go for the win. The problem is how do you maximize speed and endurance?