My mother, Ileen Wright Wardle, maintained a mail relationship, and sometimes phone as well, with numerous people. She was especially showered with card when she broke her neck and was recovering. She was working in the temple, and all shifts sent her cards signed by over thirty persons each. In addition there was Steve and Mardeane, friends form Illinois, her ward relief society, people from the courts where she worked, and many others. She also kept up regular correspondence with Dad's sisters, Audrey and Phyllis, and Audrey's children, Carolyn, Ann and Kenneth. She even saved a card from Uncle Sarah and Uncle Newell (who are actually friends, not aunt and uncle.)
In addition to get-well cards, she also received many birthday and Christmas cards over the years.
Of course there are numerous cards and correspondence she saved from grandchildren and sons and daughters. My mother has quite a progeny.