A mix of sentiments here...if you allow the stude to fly erratic circuits (several reasonable ones followed by a wide "breather") how can you possibly say you're teaching him/her properly?
Wide circuits in whatever capacity demonstrate a willingness to accept errors and that isn't good enough. Now how you go about telling the perpetrator is up to you - in this case it sounds like a one to one chat backed up by a standards meeting. D8, I accept that in the commercial world, people who fly for fun want to enjoy it - but isn't that going to shaft everyone else in the cct? And the point you made about not going solo after 10 hours isn't strictly true either, but I won't go into that as it's beyond the scope of the topic.