Why do we always make slides at the last moment?

My friend Brian posted this on Twitter and it reminded me of the situation I inevitably find myself right before a talk - making last minute adjustments to my slides! Its as if I cannot stop making changes till the last moment before I upload to SlideShare (yes, I use SlideShare to give all my talks). It also seems that it does not matter how early I start. I might start talk preparation 2 weeks before or 2 days before, I will still be making changes at the last moment.

Are you one of those people who is always working on their slides at the last moment? Or do you get them well ahead of time? Tell us about your slide preparation style?