I must admit I've known only two Erins, while I've known a plethora of Heathers, Amandas, Ashleys, Jessicas, and Sarahs. And the two Erins I knew were widely divergent in age. One was my age, born circa 1960, and the other roughly my daughter's age, born in the early 1980s.
It happened that I greatly disliked both Erins, so maybe that's influenced my opinion of the name, lol.