That's ~140 levels more than I've got. And I've completed most exp achievements and claimed all dailies/weeklies while not really overstretching and having a full-time job (it means no gaming in work hours).
So it's 480 exp/h (top), 140 * 1500 / 480 = 440 hours of extra playing time. That's 3:40 extra _accounted_ hours a day (again, compared to me) which usually translates to smth like 4+ hours/day.
My conclusion is that you only do three things in life: sleeping, working, HS gaming. And most probably one thing from this list should be crossed out. And that's not HS gaming.