The places I've worked that required time estimates (the wrong way to do it) still built in an overhead factor of ~30-40%. I.e., recognized that a dev would onl

The places I've worked that required time estimates (the wrong way to do it) still built in an overhead factor of ~30-40%. I.e., recognized that a dev would only put in 4-5 hours of 'coding' a day, with the rest taken up by meetings and random miscellany.