Thanks for both replies. In a perfect world, either of those answers would be applicable.
But I'm lazy, and I also don't know in advance that I'm putting a unit on hiatus for weeks or months; it's only weeks or months later that I realize I haven't used the unit for a long time. So given who I am, the only realistic alternatives for me are (1) just let the battery run out over time or (2) keep the unit plugged in all the time when not in use. OF THOSE TWO CHOICES, which is better for long-term battery health (and I fully concede that neither is ideal). Thanks!