I just called work. No one's there. Despite the West Coast time displayed on this page, it's getting close to midnight where I am.
So why did I call? To leave myself a message. There are 4-5 things I need to do tomorrow, and it's very possible I could forget one or two.
The act of speaking these things aloud creates a kind of muscle memory (larynx memory?) Basically you remind yourself by leaving evidence that you cared enough to remind yourself. Now whether I listen to the whole playback is of secondary importance, although it wouldn't be a bad idea.
I've done this before and I've neglected to do it. It does make a difference.