In reality you end up dealing with a flat per diem... that you have to calculate to the hour with things like crossing borders (even funnier when you have to in

In reality you end up dealing with a flat per diem... that you have to calculate to the hour with things like crossing borders (even funnier when you have to include work authorizations in there, like with Switzerland!), and you still have expense claims, which might or might not be discounted by per diem depending on type of the claim!