Just as with the "Late Work Is Not Accepted" blog, the message is direct.
Teachers should not give extra credit assignments at the end of a marking period to help students improve their grade.
Students should complete the original work on time instead of trying to complete extra work. Giving extra credit assignments at the end of a marking period is an indication of a poor decision-making on the part of the student or the teacher or both.
Yes, I have given extra credit assignments at the end of a marking period. I did so when my planning and work during the marking period was weak. The behavior changed when I eliminated extra credit work. I was forced to do a better job throughout the course. Student behavior changed when they realized I was being honest with them and would not give them extra credit work.