It's not obvious to me that the studies you reference are refuting the article. In your reference, time on task is time when students "are actually paying atten

It's not obvious to me that the studies you reference are refuting the article. In your reference, time on task is time when students "are actually paying attention to the content being presented". Some people can pay attention for long periods of time, and some can't. So, maximizing time on task does not always mean 60 hour weeks, although that might work for some people.