Never Stop Asking Why
That was all fine back in the days of Cheshire labels, hand insertion, letters typed on a Selectric typewriter and low donor expectations. (Yep, I'm an old dog — and if you have no idea what I'm talking about, you aren't!) But there is no excuse for not mailing/emailing smart, which could be more often or less often, depending on your current practice.
For any of these questions, "mailing/emailing smart" may mean you change nothing; what you are doing is just right. But not asking is the mistake that's too easy to make when we're busy, launching a new initiative, juggling the entire development department on our shoulders, dealing with turnover and new leadership, or any of the challenges we can face over the course of a nonprofit career.
This old dog challenges you to ask why from time to time. Don't just settle for "the way we've always done it," but don't throw things out before you (1) have determined they don't work or (2) have a plan ready to launch immediately that looks more promising than the old way of doing things. Otherwise, you may find yourself asking, "Why, oh why, did I do that?!!"