I’m pretty sure in our case UKentucky was mailing my son right from the start (like starting in Junior year) but yes, those “you can still apply” letters are probably quite important to kids who have been turned down by all their reaches, with no safeties. (For high stat kids, there are typically no “match” schools – just reaches and safeties. Any school that is a match for their stats is a “reach for everyone” type school.)
IIRC he also got some (not from UKentucky but places like University of Advancing Technology) toward the end of his first year of college. The message was clearly, if you’ve flunked out of your first school, try us. :-/