I send our product and services leadership team a note (almost) every Friday. I first heard about this practice from Scott Burns, of Structural, about a year ago. Since then, I've been getting progressively more deliberate and diligent in preparing for and sending a weekly note.
There are at least three important reasons to do so: you build a stronger relationship with your team; you inform and guide your team to desired actions and outcomes; and you clarify your thinking on important topics (presumably you're writing something which you feel is important).
If you're a leader of a team, especially if you have one or more managers between you and your directs, then I encourage you to write a weekly note to your team(s) - whether it's a Monday Note or a Friday Note.
1) Ten Years of Monday Notes by Jean-Louis Gassée