I also lie when giving estimates. This is the only part I disagree with. You can't lie about something you don't know, and it's the nature of an estimate that

I also lie when giving estimates. This is the only part I disagree with. You can't lie about something you don't know, and it's the nature of an estimate that you cannot possibly know whether it's right... if you did, it wouldn't be an estimate. You may present part or all of an estimate that's just not what you actually believe, but it might still end up being right if the right things go wrong. Estimates suck. I'm pretty good at estimating, and doing it still sucks; they are never exactly right, for too many reasons to enumerate. Unfortunately, in many situations (e.g. consultancy, as you mention), they are important sales tools... I'd venture to guess I'm not the only small business owner that considers estimates one of the many good reasons to move from a consulting to a product development model once the means are available.