At some companies I'm familiar with, the highest level ICs have nearly unlimited freedom to "move on to the next project" as you put it. Some slot themselves into purely advisory roles, so they can dedicate their time to accountability-free control without ever having to risk assuming responsibility. Others constantly flip through greenfield development projects, leaving maintenance teams behind like mouse droppings once the projects are too mature for their tastes.
At Google, high level ICs seemed accountable by most standards. They couldn't just abandon projects when they became boring, they got in trouble when their projects didn't work well, and the weird committees (which admittedly did exist) generally felt like guideposts more than obstacles.