Back in the bad old days of Intel Macs, I had a full system crash just as I was about to get up to give a presentation in class.

It rebooted and got to desktop, restoring all my open windows and app state, before I got to the podium (it was a very small room).

The Mac OS itself seems to be relatively fast to boot, the desktop environment does a good job recovering from failures, and now the underlying hardware is screaming fast.

I should never have to reboot, but in the rare instances when it happens, being fast can be a difference maker.