I’ll just add a general comment or two. JS describes his method as “magic,” which I think he means in the sense that fitness exams up on you unexpectedly and can last throughout the year without periodization, per se. Forgive me if I’ve got that wrong.
When I was being coached and made some strong improvements as a young masters runner, I had a similar view of my coach’s training, as the aerobic conditioning made me feel like an aerobic monster and subsequent broad phases of training put me in very good (for me) race fitness across a broad range of distances (1500 to HM, maybe 800 too) throughout the year with little conventional periodization and relatively little race-specific sharpening. A key difference between the training I experienced and what JS describes is that the aerobic development used a few effort levels / paces slower than - but building up to - M pace, and never got faster than M pace. Training for ST runners may have included some faster long interval work, but as a strong-FT runner I never touched anything faster than M pace, and snuck up on that very gradually. I would also see those effort levels occasionally out of base training.
I’m not suggesting that approach is better than JS’s “magic,” just saying it worked really well for me in the past, and also worked quite well for a number of other folks I know.