During the main build season, I spend about 33 hours/week doing robotics-related things. But during the crunch week, I usually spent 14 hours/day (or in other terms, over 70 hours during the week before ship!) at robotics getting everything finished in time to ship.
(I have winter vacation during the last week of the build season every year, so I can spend all day from 9 AM to 11 PM at robotics. 
)