This was available in Test/Quiz, but it is not available in Assessment. The only options in Assessment are final score and last score. I used to use average score in Test/Quiz and give students two attempts. If they figured it out, they could copy their correct answers and just worry about the questions they got wrong. But, with average as the final scoring method, they new answers would work out to being half credit. I also gave them unlimited attempts with average scoring turned on and let them retake it until they were happy with the score. Some students would try a quiz 10 or more times trying to bring up a less than perfect first attempt. I then got to explain how averages worked.
I know I could just switch back to Test/Quiz, but I converted everything to Assessment 2-3 years ago when I was told that Test/Quiz was going away. If there was an easy way to convert them back, I would. But, now I would have to re-enter all the questions, responses, and answer comments.