I agree with you, it certainly makes sense in my opinion to question the credibility of predictions based on a history of bad predictions.<p>For example, I am ridiculously bad at estimating how much time implementing features / fixing bugs would take. Most of the time I'm really off, at least by a factor of 2. Surely my manager should take this fact into consideration when asking me how much time something would take me when planning the timeline/schedule (he does, in fact).