Excellent advice! All friendships are a little bit different and that is OK.

When you mentioned A Tier and B Tier friends, I could immediately think of people who fit both those categories in my life. I have a friend from high school who has sent me a birthday card every year for the past 35 years! Every. year. And I do the same for her. There is another friend who lives down the street and we chat when we bump into each other, occasionally meet for lunch, but that's the extent of the investment. I use to try a lot harder with her, but I stopped and then we found a comfortable friendship for both of us!