Rosewall I made a new image with your different target zones for attack and counter-attack. I also then highlighted the area in Green which is the zone which is shared by both attack and counter attack
and highlighted the Smart Targets in Yellow.
The zones you speak of are the traditional type of thought which 5263 says are outdated, and not supported by actual play results. However, this is not meant to be accusery, since I thought the same as you before this thread started lol!
The biggest thing to take away from this diagram is to see that the shared zone is a triagnle, very similar in shape to the Smarter Targets. However, the big problem is that the zone leaves no margin for error. We are assuming you aim for a specific point within that one, so if you pick the line you can't miss that spot long at all without losing the point.
the Smart Zones provide an answer to this problem by providing a margin of error. If you aim for the deepest part of the zone then even if you miss it long by 3 feet, you're still one foot within the line!! (and Aim is improper when talking about tennis but no other word i can think of really captures the idea of trying to hit to a specific point...than aim?)