On the social media and in Larry Ferlazzo's EdWeek piece on the topic, the old debate about student late work has been churning again.
This debate will always churn, because three things are true:
1) Deadlines are a real thing in the world, often carrying some serious penalties.
2) Giving a student a grade on being late means you haven't actually assessed the skills and knowledge that were supposed to be involved in the work.
3) Some students face much larger obstacles to meeting deadlines than others.
A teacher needs to balance all three true things in their brain.
A hard and fast, take no prisoners approach to deadlines is unnecessarily brutal. These are, after all, not full grown adults. Requiring them to meet deadlines without support or slack is setting them up for failure.
A lose and floppy "just hand it in any time" approach is not doing anyone any favors. It's not fair to students that one gets three days to complete the assignment and another took a month. And it is absolute nightmare fuel for teachers, who face a jumbled mess of grading.
I taught a course that was heavy on writing assignments and therefor heavy on deadlines. In a typical 9 weeks grading period I had 50-60 grades in the book. That's a lot of paper to process, and a lot of deadlines to meet. Here are the principles I followed that kept me sane and my students mostly on track.
No surprises. Let them know what is coming, and then keep telling them it's coming, and then keep telling them how long until the due date. You don't have to be irritating and naggy about it; just keep them informed. But unless you have some reason to include memory skills in your class learning objectives, there's no reason to make students depend on the memory capacity of their half-wired brains.
For larger assignments, give more than enough time. Don't make the mistake of giving students the amount of time that would be enough, but only if those students didn't have any other classes or responsibilities in their lives.
Mix it up. Not all deadlines need to be created equal. My students could usually hand regular homework assignments in whenever. But I also had assignments that were "Absolute Deadline" assignments. Just be explicit, so that they know what's coming and can organize accordingly.
Provide supports and scaffolds. One of my biggest mistakes in this area was the first year I pioneered a massive research project. We talked about it and I gave reminders, but there were no actual deadlines until the final one, and for some students it was disastrous. In the following years, I added secondary deadlines and check-ins (just come to my desk and show me what you've got) as part of the process; it helped keep them from digging themselves into too deep a hole. And when they dig that hole, help them create a plan for climbing out.
Be open and humane. Run the kind of classroom in which a student feels safe to come to you with whatever struggles they're facing doing the work. I've had students miss critical class time because of terminal illnesses of parents. Once a student's house burned down with her work in it.
Be selective about what hills to die on--and then hold the line. My policy was that small assignments like homework or mini-essays written in class time could be turned in late at any time. But at the end of the nine weeks, when my own grades were due, the final absolute deadline was absolute. If it wasn't in, it was a zero. Absolute deadline assignments worked the same way, with steep penalties for lateness.
Not everything in life is a hard and fast deadline, but it would be misleading to suggest that such deadlines do no exist. Our major local employer has a simple policy, written by management and union together-- after a certain number of unexcused hours, you get a warning, then a meeting, and when you hit the max, you're fired.
It helps to keep your focus on what you are actually trying to teach and therefor what you actually want to measure.
But it's also fair to include "responsibly meeting deadlines" to the list of things you're teaching. Meeting deadlines is, I think, one of those things that most adults do without any consciousness of how we do it or when we learned how. But human beings are not born with innate knowledge of how to meet human-created deadlines, how to organize a project and apply the time and resources to it. Too often the only advice we have for young humans is "well, just do the work" or "buckle down" when they don't actually know how to do that. And if they are in a chaotic life situation that they cannot control because they are at the mercy of adults, then simply repeating "work harder" or "clearly you just don't care" is no help. You'll also see students dealing with task paralysis, a situation where they have so much to do that they literally cannot figure out what to do next, and so time passes and more work piles up and their anxiety rises and they fall further behind rinse repeat--they are unlikely to break out of that without someone helping them chart a path.
None of this means abolishing deadlines and consequences for them. It is no help for students in the long term to be taught that no deadlines really matter and you can just do, or not, as you wish. But it is also unhelpful to simply point at a deadline and say, "The hammer is gonna fall, kid, so you'd better deal with it, somehow."
Part of what we're supposed to teach is not just how to pack knowledge into your head, but how to transport it out of your head and into the world, and to do it, sometimes, in a timely manner. To teach the learning without teaching the How To Get It Out Of Your Head part is incomplete teaching. Deadlines, with consequences, are part of that learning. But requiring deadlines and penalizing deadline failure without providing support is like giving a unit test without teaching the content of the unit.
So, yes, deadlines and penalties, but not always deadlines and penalties and not just deadlines and penalties.