it's extremely hard to account for bugs that aren't discovered until later. Pad your estimates, because you are typically going to have similar bugs (for simil

it's extremely hard to account for bugs that aren't discovered until later. Pad your estimates, because you are typically going to have similar bugs (for similar projects), and you can account for those unknowns probablistically. You don't know the exact bugs that will be found, but you've already predicted that some will be found, so include that in your estimate.