Yes, there's a classic blig post (sorry, no bookmark handy) about an analogous trip from SF to LA.... Also, (maybe counterintuitively), in software estimation

Yes, there's a classic blig post (sorry, no bookmark handy) about an analogous trip from SF to LA.... Also, (maybe counterintuitively), in software estimation the more fine-grained the estimates, the more likely they are to _underestimate_ project scope. For areas that are better-understood, the estimate will be (properly) limited in scope (reducing the overall buffer) -- which leaves less margin for error in the areas with more unknowns, where the biggest scope bloat is hiding. As a rule, software estimates should use a very broad brush. (This also helps mitigate the tendency of PHBs and product owners to mistake precision for accuracy.)