Here is a link to another interesting article on the Study Hacks blog:

Study Hacks:  "If Your're Busy Your're Doing Something Wrong"

Once again, the important point is this:  it is not the amount of effort, but rather well-directed effort that determines success.  Effort is the essential first step, but no amount of time spent on a task can overcome bad study strategies.

A point I would question is the implied value of "marathon" practice.  The article states that 3.5 hours of practice a day, divided into two sessions, is enough for the elite achievers.  While this may work for musicians (the subject of the article), I think this ignores the value of distributed practice-- studying several times a day, every day, but in short, directed sessions.

And again in this context I define studying as practicing the recall of information.  This is a different activity from extracting new information through reading a textbook, attending class, or completing homework assignments, which does require significant blocks of time.