That's not a bug, it corresponds with real life operation.  
What is a bug and is incorrectly modeled on many aircraft is that those that had injection based WEP systems were of finite duration.  In AH, even in aircraft that had a finite amount of WEP in real life, you can "cool down" after using WEP and re-engage it.  In real life, when you used it up, you were done for that sortie. (i.e. until the aircraft was serviced).  
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