I agree. This would need to be tested thoroughly before it could have any degree of certainty attached to it.

I would also argue that the remaining roll shouldn't be reused for other customers anyway (if it has been sitting out on a table for hours), thus rendering it unusable and therefore a cost. The restaurant owner might inadvertently find themselves wasting the +1 roll - or it simply being eaten anyway!

It's a nice, thought-provoking story, but I wonder how applicable to the real-world this really is?