Hi Sabrina:
If anything beyond what is stated at the beginning of class is given, it better have to do directly with course assignments requied by all, and graded in the same way.
Good students who do all required work can feel slighted if they feel other lower performing students earned points they were not offered. They may even feel it's unfair to give any extra credit at all.
It's a balance. Sometimes it's a policy. For me it's a simple concept: learning and teaching vs points and grades. Both are used, but where should the enphasis be?
Regards, Barry