[Rules] Lets talk about Smoke baby

[waynebaumber]

I have come across two interpretations of the smoke rule and I am curious to see what the rest of the community think

In the optional rules for smoke under limited ammunition it states that each side has a number of turns of smoke equal to 10% of turns in the game rounding fractions up. I.E in a 32 turn game you get 4 turns of smoke.
Now I have always played that as written, so in the above case you can fire smoke on four turns in the game. However my new opponent has mentioned to me that he and other believe that this applies to each on board artillery/mortar and each off board artillery increment separately.  So in the above game if you had two on board mortars and two off board artillery they could each fire smoke 4 times. This of course could result in 16 turns where smoke could be used.
Their rationale for this is that the rules state to track usage place a smoke marker under the firing unit. 
Which of the above is correct or should I say which of the above is closer to the intent of the original rule.