+3 -- and one should focus on completing the task, not the number of hours. If you give it 40 hours, it will take 40 hours; if you give it as much time as it needs followed by beer at the beach, it will take 20 hours or less.
I worked and went to school, then after that, got multiple jobs. Sometimes one job is just a kind of hedge against another job's instability. Or, maybe one job has risks associated with it that another one doesn't. I think kids coming out of college SHOULD get multiple jobs and do them until 30, and never work a week with less than 60-80 hours.