I'd name every object that takes one. Letting the defaults do the naming for you leads to issues down the road, if nothing, in clarity. When you compare your development and production boxes and all the index/Pk/fk/whatever names are different, it makes tracking who changed what when much more difficult.

As far as what naming standard you follow... I really don't care. Go for clarity and consistency and make it easy to use. That's all. After that, I'm easy, child_fk_parent, works, parent_fk_child, works, childparent, works, parentchild, works, parentchild_fk... I'm easy, let's just make it clear and consistent.