Students invariably prefer group portions to the testing, even though the results do not seem to be significantly different that the individual portions. I sometimes give a problem on the individual portion that had already appeared on the earlier group portion, at least in part. Or an individual problem may focus on one aspect of a larger group problem. I think this encourages learning to take place during the exam. Quizzes have both a group portion and an individual portion.
Students appreciate group quizzes and testing.
I have yet to decide a set method to group quizzing and testing. If a particular class does the majority of their class work in groups I feel testing should have a group portion. The weight of each of these I am still investigating to my own satisfaction. At the same time I feel it is necessary to evaluate individual performance. I always try to be careful not to incorporate too much group testing into the semester, or else I lose track of how individuals are progressing in their competence.