I ran a 4:27 1600m six years ago training on roughly 40 mpw. I have been jogging 15–20 mpw since, never ran faster than 9:20 for 3000 or 16:00 for 5000. Ran 16:22 in an xc race after the spring of the 4:27, consistently running in the 16:20s.
Never ran an official 400m or 800m. I ran a 55 in flats and I split a 2:06 in a 4x800 on 20–25 mpw a few years before I was in 4:27 shape. Presently, I can run 3 miles in 17:00 and probably a 4:58 1600.
I have not run faster than 4:00/mi pace in a while, but I would estimate a 400m TT to be 58/59 currently, dropping to 57/58 just from time trialing a few times with no 400m specific work. I don't really care about 400m/3000m/5000m times, I want to embrace the 800m. To do this, I want to use the 20–30 mpw Jack Daniels 800m plan, will this be sufficient?
The last question I have is about the 5-second rule (read about this in Rubio's guide, instead of the 4-second rule for around 5-minute milers). If I can run 58 currently, 58 + 5 = 63, which is a 2:06 800m. I would love to hit 2:06 again unattached in the spring in some local D3 meets. Could Daniels' plan get me there? Also, interestingly Daniels suggests that a 58.0 400m is a 2:07.6 equivalent, while 57.0 is a 2:05.4 (Table 10.1, Daniels' Running Formula 4th Edition).