I just found this quote from the Mythical Man-Month by Fred Brooks. I have read the book before, but must admit I failed to see this quote. It is almost comical how well this describes reality.

It is very difficult to make a vigorous, plausible, and job-risking defense of an estimate that is derived by no quantitative method, supported by little data, and certified chiefly by the hunches of the managers. — Fred Brooks (1975)

I always had an inkling to learn more formal ways of software estimation than the ones I practice. It would be nice to deliver an estimate with a bit more comfort. My current estimation method revolves estimating the complexity, looking at the past mistakes, and adding a decent buffer. That quote from Brooks is just plain awesome…