It seems some of your ideas basically amount to “no techniques really work, and people only think they work because of random variation and measurement error and stuff”. Not sure how plausible this is.
Though it would be odd (and require a strong explanation) if no productivity techniques do work. Which is like saying, no medicines really work, it’s all just placebo effect etc. Since productivity fails for particular reasons (e.g. procrastination), and presumably techniques (like medicines) can be designed to fix or at least mitigate those reasons.
Currently, it’s pretty darn plausible.
Though it would be odd (and require a strong explanation) if no productivity techniques do work. Which is like saying, no medicines really work, it’s all just placebo effect etc. Since productivity fails for particular reasons (e.g. procrastination), and presumably techniques (like medicines) can be designed to fix or at least mitigate those reasons.