It didn't happen often, but sometimes, a listener would call the radio stations at which I worked long after a contest ended and ask if we had a winner yet.
I would never tell a caller outright, "The contest was two hours ago, and the tenth caller got through within one minute of my announcing the contest." I would just say, "Yes, we have a winner, but thank you for listening."
Even if you work for a low power station that only averages five listeners at a time, it's human nature to want to win cash, concert tickets, gift certificates, or free music. Almost always, the phone would start ringing immediately when I announced a giveaway. Some of the same callers probably got through more than once. There might have been a contest or two in which someone won by being the only caller.
One repeat caller is all it takes, however. Even if you don't know any music by the artist whose recording you could win, haven't eaten at the restaurant where you could score a free meal, or have no idea what gifts you would buy with a certificate to a sponsor's shop, it feels satisfying to be a winner. Those victories seldom go to procrastinators.