By the time you get to my age, your list of potential Anna's will be in the high dozens. You simply cannot keep this up with all the Anna's. A lot of people genuinely don't want to hang out with you. Likely that number exceeds the "real" Anna's by an order of magnitude. If there's someone I particularly like, I'll keep inviting him. But if the person is otherwise normal (e.g. clearly has a social life), I invite 3-5…
These days I know a lot of busy people, so my softer version is, if I invite you to a thing and three times in a row you don't even reply, I'll probably just quietly stop inviting you altogether. I'm ok to keep you on the list if you make the effort to reply and explain why you can't come.