On the PDF it says “No Organized Practice” so there is your rest.
Even in the late season he is asking for 3×350 through 200 in 24 and most of the 200’s at 28/30 second pace. That is for a 46 runner. You might want to go over it again in a bit more detail.
Going through 400 in 50 point and holding on for 50 and then doing 3×200 in 30 won’t bother most 46.0 guys.
You scale the workouts down to your level, so a 51 runner would go through 400 in 55 for a 450.
The 450m workout may seem relatively easy for a 46s runner, but remember that the guy competed 2 days before.
The 350m workout is tougher, the speed may seem slow but the short 5 min recovery is what makes it hard.
I have at least 4 different 400m programs from coach Hart. The one quoted here seems to be the latest one. Earlier versions, like the one in the USATF coaching manual from 2000 included faster 200s, predominantly in 26s with 200m walk rest instead of the 30/30. Still not very fast, but a significant change nonetheless.