Hello Anne,
Giving a student one-on-one attention is always a smart thing to do. I have seen unfocused students become really focused having the individualized attention. I generally work with a student one-on-one without any other students being present, however, I understand your perspective as well. Some of my unfocused students are easily distracted, therefore, I prefer to have one-on-one with the student without anyone else watching. I tend to stay late or come in early to work with students one-on-one. It is always challenging to get unfocused students caught up whenever they miss class. You are on point, you can not reteach the entire lesson because a student missed. Time is of the essence, and you must move forward.
Patricia