Agreed, except in cases where the code will never be maintained again (e.g. game releases on N64). In my experience an "over-estimate" that leads to the so call

Agreed, except in cases where the code will never be maintained again (e.g. game releases on N64). In my experience an "over-estimate" that leads to the so called "do it right" syndrome happens if someone else estimates for a developer. When the developer makes the estimate him/herself and doubles it, you can be damn sure they are going to need all that time and then some to even get it in the ballpark of long-term acceptable. (That being said, the company needs to have standards for code acceptability in the first place, which doesn't always happen)