I too notice the shorter burn times (although still quite long IMHO) with Royal Oak Briquettes and other "ridged" briquettes. Honestly with the 30 gallon drum as opposed to 55 anything I cook seems to get cooked.
I would encourage you to try Kingsford Competition. Smells good and burns good. It's just hard to find.
Primo XL, Pit Barrel Cooker, Mini WSM,Lodge Hibachi
Craigslist finds Tiernan SOB, New Braunfels Black Diamond, Big Green Egg Mini
By the way, did she mention my name-just in passing?