My primary interest in using the Bob System and some sort of scoring system is in formative assessment.
When I have a clear understanding of how they are doing then I have the ability to try to make my training more effective in two ways.
Tracking this sort of information can be very useful in other ways, as of Action Research in the classroom. If you are monitoring many aspects of the student's performance in the classroom and you have a student who always participates correctly, does the pairwork, groupwork, homework, listens and doesn't goof off but does not seem to progress in their English from one term to the next then that would raise some very good questions for the teacher.
[Photo: Some of my 300 college students that I taught weekly last term doing pairwork. Next term I will have 400 college students each week.]