I recently read an autobiography by a top runner and it was like most. To paraphrase: "When I started running, I tried A and it didn't work. Then I heard people had success doing B, C and D, so I started doing those and started to improve. Then I followed a rigorous plan of B, C and D diligently and improved quickly. When my progress started to slow, I wondered if I was missing something. I heard about E, added it and had peak performances, so E is the secret to success; if I had been doing E from the start, I would've been even better. Then I added F, but not only didn't I get better, I got worse, so I went back to what I had been doing earlier, but I kept getting worse - F killed my career. Never do F. If you follow what I did, you'll have the same results."
It doesn't matter who the athlete is or what A through F are. This is simply a description of a running career. Little success at first, then fast results, then diminishing returns and then a trailing off. That's my story, that's your story. The whole argument is fallacious.
1) If something doesn't work, perhaps you didn't give it enough time. Perhaps you didn't do it properly. Perhaps you needed to do it after doing something else first.
2) If something works, it works temporarily. Perhaps something else would've worked as well. Different things work at different times.
3) What works for one doesn't work for all and doesn't work equally when training for different events.
When you train, try something for 6-8 weeks. Then make a significant but not complete change; you might add something or change something or remove something. Then try 6-8 weeks under the new plan; if things don't improve, go back to what you did before for another 6-8 weeks and then make a different change.