Not in year 11 anymore but mine are/were called mentors and you had a similar system and we have to remain in library or we can leave school if its last period.
You were expected to study, I used to do a lot of work at the start of it but eventually got more comfortable and started talking to the few people with as many mentors as me year 11 and hardly got any done. Now in year 12 pretty much everyone has them and its hard for me to do work tbh unless I put my head down sit isolated and have music on high volume. I pretty much just do my homework in these periods, usually Maths ( do ext too) because its by far the most I get.