Mastery Learning, which Bloom advocates for in the two sigma problem paper, is an alternative to 1 on 1, not a way to achieve it. What you describe seems to be

Mastery Learning, which Bloom advocates for in the two sigma problem paper, is an alternative to 1 on 1, not a way to achieve it. What you describe seems to be a very poor implementation of mastery learning. But if the tutor is completely disengaged even 1 on 1 tutoring is unlikely to have good effects.