During my corporate gig, we engineers had a non-written rule of thumbs to estimate sheduling: Think about how much time do you really think it will take to do i

During my corporate gig, we engineers had a non-written rule of thumbs to estimate sheduling: Think about how much time do you really think it will take to do it, double it, and add 20% contingency. This worked well most of the time, as usually we tend to be far too optimistic.