My limits are that it has to be reasonably close to what really happened to school kids in living history. Not exactly the same – I’m 18 and I can take more than a little kid can but it is pretty close most of the time to that.
It is my belief that a school caning at the age of 18 or 25 doesn’t hurt any less than it does at the age of 12. I would also suggest that it is no more painful for the 12 year old than the man of 18. The key difference is in the mental strength of an adult and whether you are taking the punishment willingly.