Here is another view point.
I work in a patchwork shop and the number of customers who do not use rotary cutters safely or correctly is amazing.
Maybe rather than have a extra class the tutor could spend a small amount of time at the beginning of the lesson to check that customers are doing the right thing. So that their pieces turn out the right size.
Unfortunately just because they have made a few quilts doesn't always mean they know what they are doing.