GTF, no I haven't yet completed a marathon. I attempted it twice in college on, admittedly, poor training and DNFd both times. I had derived confidence from my latest approach because it took me to being able to run over 2 hours (something I've struggled with in the past) relatively quickly and I felt like the cycle was going well. I don't think I would care so much about the mythology of the marathon as you call it if those 2 DNFs didn't bug me so much.
I am interested in what you say about the supercompensation cycle inducing greater adaptation over a day 2-3 day cycle rather than a 4-6 day cycle. Do you have anything to back that up? I'm always interested to read that sort of thing and I had never heard that before.