I used to send out thirty-some Christmas cards every year, and I always got at least half of that back. I got more when I was with my ex, because all his friends were on the list too. But I made a guideline that if I sent someone cards for two years and got nothing back, that the third year they were off the list. I just couldn't do it with all else I had to do. Now I don't send out any, although I keep a stash for people like my neighbors and such that I just give them. I got so few back that it wasn't worth it, and most of them were from family that I talk to all the time anyway. Almost all of the people I was friends with in high school and college I kept in touch with via cards, but gradually they dropped off the list.
I had one high school friend that lives here whom I had a falling out with after I went to work where she did and she became my boss. It didn't work out for me there and we just faded away. I left the door open; if she had contacted me and wanted to see me, I would have been happy to, but the last time I heard from her, she wanted me to watch her pets while she was away. That was after not having heard from her for a YEAR. Excuse me? I don't hear from you for a year and then you send me an email "Can you feed my dog while I'm on vacation?" I sent her a polite email back to the effect that it was great to hear from her, I hoped she was doing okay, sorry, I was busy that weekend and I just couldn't do it. I haven't heard from her since. I would still see her if she wanted me to, but I'm not going to initiate it because it's clear she no longer values my friendship.