lower the nose to achieve 665 fpm rate of descent in still air conditions.
Hmmmm, and what if it isn't still air conditions?
I think a slightly more flexible approach is preferable.
I would also add that if incorrectly spaced, orbits on downwind are not a good idea, preferably go around and try again. Of course we all know how to go around from any point in the circuit and not just on final, don't we?