Middle distance runner here, disagree with most of this. I agree that there's not much point for a beginner runner to worry too much about form. However, simply

Middle distance runner here, disagree with most of this. I agree that there's not much point for a beginner runner to worry too much about form. However, simply running a lot does not give most people efficient form (it does prevent them from having horrible form, but doesn't force them to have good form). I have a friend who has been running 60-70 miles/week for a few years, and his form is still quite poor (and this limits his speed for middle distance races). Also, I don't have a source to reference, but I do not believe your "pro tip" at all. I'm quite sure running efficiency goes down as fatigue increases. Common advice is to focus on your form when you start to fatigue, because this helps you keep efficiency up. Finally, I doubt any of the "elite" runners referenced in that video have the form they have just by running a lot of miles. Running efficiency is something to think about and to work towards, not to just acquire by running a lot (of course, running a lot helps).