This has been an interesting thread and I have gained an insight. This past weekend I had an athlete run 1:49.78 for 800m. The interesting aspect is that he didn't start training till he was 21 and achieved the time at 25.
His training is on average 25-30 miles per week and most of his training is done at threshold and 3k pace.
We do little training at 800m pace although he has a pb of 48.2 for 400m
Today his session was as follows:
1k in 3:15
3x400 in 70 seconds on short rest
3x400 in 600 with 2 min rest
4x200 in 26 with 2 min rest
He has Nationals in the next several weeks and we hope that he can make the final in our country. Our other athlete has run 1:50.15 off similar training and 3 weeks ago he was doing 6x1k in sub 3 minutes on grass. Don't neglect aerobic fitness.