I just had a look at my rescuetime statistics and this is an attempt  to interpret it.

Week             no. of hours      Efficiency**   Effective/Productive working hours*
 july 10-16     59h 51m           -0.7                27hr 20min
July 17-23     70h 21 m          -0.37               30hr 11min
July 24-30     57h 8m             -0.16              17hr  40m
July 31-Aug6 74hr 14m          -0.91               8hr 25 m
Aug7 – Aug 13 25hr 24m       -0.15               10hr 44m
Aug14-Aug20  42hr  28m      -0.19                26hr 04m

**- As displayed by rescuetime
* – (just summed up by category, including 0 productive hours)

The clear conclusion to be drawn is am more efficient when i work, nay spend a lesser no of hours on the comp.
Perhaps, not very surprising. I think i should target 50 hrs a week on the computer.
Note that 70hrs a week does result in 30hr on productive tasks but still a -0.37 efficiency…

P.S: i know the efficiency and working hours doesn’t add up or make sense, because rescuetime uses a
weighted average for efficiency. Weighted by productivity of the task(user-defined) from -2 to 2 integers.