This sounds about right for focused thinking work. Also probably an average. For me if I'm really in deep on a problem, then I work much more than that as I try

This sounds about right for focused thinking work. Also probably an average. For me if I'm really in deep on a problem, then I work much more than that as I try and figure it out, including evenings and weekends. But... once its done, that might be followed by some "light" work days.