[elevensies]

I am probably thinking here at a different level of granularity than you are, I would be talking about days to weeks here. I can't recall ever repeating the same task. It helped by letting me notice systematic errors and by helping me calibrate optimism / pessimism.

In my estimates I was focused too much on development time and not providing adequately for testing and deployment. On an existing project with the procedures already well in place it was fine, but for new or new-ish projects I was always under-estimating.

The other thing was calibrating my margin of safety. I now typically estimate at 2x the time that I think it will take to allow for unexpected issues and unrelated tasks that always pop up. That also works for me with the expectations of the people that I work with -- the estimates are used for planning and coordination and aren't effectively deadlines, but if I underestimate too often is causes coordination problems with the business people.