Maybe the development is going better than planned and they've decided to wait a day or two, and then announce that they're done? *Huge optimist?
As a developer, I can tell you, things ALWAYS take longer than you estimate.
That's why it's a love hate relationship with contract work for me. I love keeping my own schedule, I hate giving estimates.
True, but generally you give estimates in work (billable) hours not calendar time. Although, you can extrapolate of course.
But, where I work we always underestimate, but it's the nature of the beast, there are always things you don't anticipate so you don't consider them in your estimate. That goes for most engineering things, from software, to construction to road work, to accounting.
It's worse in software because you are always doing something new. While in construction you build the same house the same way hundreds of times so there are a lot less "unknowns" that come into play.
