Why, then, do I bother with midterm grade warnings? Students who have made it a habit of never doing the work will not easily break that habit. One warning and a stern talking to will not do it. Failing the class will. Retention is bullshit. We shouldn't be trying to retain them, but get rid of them. Those students without the necessary habits of mind to succeed are a drain on the resources of the university, not an investment.
Alternately, we could train them in those habits of mind. That's the route the more compassionate and less annoyed part of me would prefer. But try suggesting that one at a faculty meeting or to an administrator.