Hi Gerry:
I believe in giving grading criteria at the beginning of a course and, unless very unusual circumstances divctate otherwise, I don't change the "rules" midstream.
I believe good students probaby do all assigned work and extra credit work whether they need the points or not. Slackers will depend on extra credit in order to just slip by.
Good students will view the extra opportunity given to slackers as special treatment and, possibly consider it unfair. The last thing I want to be accused of is showing favortism or unfairness.
If too much "EC" work is allowed, it skews… >>>