I can attest to the fact that Shannon will definitely try and push the corporate line as far as she can, but ultimately, and changes or decisions are made by three people not directly associated with Mythos-1) The Head Chef in charge of all OU restaurants (good guy, very knowldegable, responsible for most of the success the UO foods division has enjoyed over the last decade), 2) The UO sous chef (pain in the ***, loves to constantly bag others ideas, the opposite of a visionary), 3) the VP in charge of foods (very intelligent from a monetary standpoint, but cost concious to the point that quality/service can suffer. She would also be responsible for Shannon's promotion, so she does have my gratitude for that decision).
So, my point being, Shannon and Mark may have grandiose visions of what can and can't be, but after all is said and done, any changes have to be dissected ad nauseum, then approved. This is why you don't see change more often on UO menus.