One thing that really grinds my gears is when students claim that they "didn't have enough time" to finish an assignment.
Our school system policy is to allow students to turn in late work with no penalty to their grade, which, okay, I can accept because according to the standards we are supposed to be evaluating demonstrated academic ability, not behavior. It also helps that we are given (some) flexibility to set harder deadlines, so that we don't receive a metric ton of work at the end of the term from students who are scrambling to pull up their grades.
I think I want my policy to be "once I return an assignment, I will no longer accept it for credit." Ideally I'd post a running tally of how many had originally been turned in and how many I've evaluated so far. Generally, the more work an assignment takes from the student, the more complex it is to evaluate. That would give me more of a sliding scale so that my deadline is both clear and flexible.
Additionally, we allow students to re-assess, so long as they complete a contract identifying problems they encountered and make a plan (usually including additional work for practice) so that when they complete the assessment the second (or third...) time, hopefully they'll do better. But when I see "I didn't have enough time" listed as one of their problems it sends my blood pressure skyrocketing. Because, see, there was additional time available - I am here before school starts and after it ends. I allow students to come in from any of their other classes to work, so long as they have permission from their other teachers. The library is open before and after school and during the lunch periods.
Did you use any of those opportunities? Did you even ask about them? No? Then don't you dare claim that you "didn't have enough time."
Continue...

Right now, I hate teaching.
Why is it so hard for me to keep in touch with parents? I usually don't have any trouble speaking with them, and it doesn't take that long to call and touch base... I just don't get it. What's wrong with me? I had a schedule set out for myself this past semester, but I didn't stick to it. And I really don't know why.