Often, they’re grading your papers on evenings and weekends because the conventional work day is already saturated with other obligations. You would do well to approach every assignment by putting yourself in the shoes of your instructor and asking yourself, “Why did she give me this assignment?
The professors are grading your paper on the weekend or in the evening because they need to work during the day and have other things. You should put yourself in your professor's shoes and ask yourself. How would your professor feel if you were in their shoes? To see how they feel. The professor has their own life and needs a break from grading and teaching. Sometimes you need to remind them that they have a life outside of teaching and grading your homework. If they forgot to grade your homework, you can politely email them to ask them to grade it or remind them, since they are so busy.