I think that the author dramatically underestimates the difficulty of learning a foreign language, which undermines his perspective statement. I would go so far

I think that the author dramatically underestimates the difficulty of learning a foreign language, which undermines his perspective statement. I would go so far as to say that it's absolutely impossible for anyone but a savant to become conversationally fluent in a foreign language with 30 hours of work which is what his timeline suggests (and the very article he links as support seems to agree with my assessment). With that out of the way, I find that my daily productivity isn't limited by available time so much as available willpower (which we currently believe can be exhausted in the same way that muscles are exhausted [0]). I think a more effective way to improve your productivity is to ask not how much time you're wasting, but why you're wasting that time. [0]: https://en.wikipedia.org/wiki/Ego_depletion https://en.wikipedia.org/wiki/Ego_depletion