@charettes I actually think that the example you provided indicates what I would consider a deficiency of the ORM: coalescing multiple calls to order_by with the same argument (I have modified the original queryset in your example):
>>> children = Child.objects.order_by('saved_dt').all()
>>> list(children)
[<Child: Child object>, <Child: Child object>]
(0.001) SELECT "prefetch_child"."id", "prefetch_child"."saved_dt", "prefetch_child"."parent_id" FROM "prefetch_child" ORDER BY "prefetch_child"."saved_dt" ASC; args=()
>>> list(children)
[<Child: Child object>, <Child: Child object>]
>>> children.order_by('saved_dt')
[<Child: Child object>, <Child: Child object>]
(0.000) SELECT "prefetch_child"."id", "prefetch_child"."saved_dt", "prefetch_child"."parent_id" FROM "prefetch_child" ORDER BY "prefetch_child"."saved_dt" ASC LIMIT 21; args=()
I would hope that the second call to children.order_by('saved_dt') can return self since the queryset is already sorted by the desired key.