I use subitems pretty heavily in my todo_notes.md file as well; to work around the concern over conflict of state, I pay attention to only the checked status of the `large task`. If that parent is not checked off, I know there are still pending subtasks. So I won't really care if there are un-checked subtasks; as long as the parent task is checked I know I can ignore it and move on. Maybe that could be formalized a bit more strongly but since it's only my eyes which will see my todo 99% of the time, I'm fine with it and I know the convention.