Why did my teacher do this?

I don't know if college board has everyones due date for the iwa and irr for the same date but ours was april 30th. She informed us of this due date on maybe april the 10th or somewhere along that date. Keep in mind shes continuously stacking us with extremely long assignments like i mean a couple pages long with only a couple days where she let us work on it in class. Randomly my teacher says if its not turned in by tomorrow (april 18th) its a 0/200 points. I turned it in already but im just so confused why she would do this, Not only did it ruin the quality of my essay (due to rusning) but it also made then entire class unnecessarily stressed out.