[dejv]

I used to work more randomly when I was starting, but I am now having strict routine with set working hours. That makes it easy to bill by man-days.

Decision is usually by customer, I am trying to go with having man-days as billable unit as much as possible, but it is not battle worth winning every time. At the end what customer want is having clear idea how much is project going cost and trust that quality would be (at least) good enough.