All during workshop week and even into Recruitment, we keep checking our fax machine because they keep coming. Many alums call the house, the House Director, and advisors to give "phone recs". The majority of the time it's "I just found out Suzie was going through Recruitment..." or "I didn't know when Recruitment started..." I've had alums call the night before Pref.
We don't have an official cut off date, but I tell these late alums that there's no guarantee. If we have the time we'll do it, if not then the PNM is out of luck.
My favorite quote that has become my Recruitment mantra: Your failure to plan ahead does not constitute an emergency on my part.