Schaffer vs. Neilsen

Harlow has us reading Robert Schaffer's High Impact Consulting. Some (though not all) of Shaffer's recommendations to consultants (and more importantly, clients) seem to be in direct conflict with Eric Neilsen's advice in Becoming an OD Practitioner. Most notably, Schaffer recommends that a consultant contract for "results" rather than "deliverables," whereas Neilsen suggests that a consultant contract for activity, not results.

Deliverables are not equivalent to activity, but I think the terms imply the same sense of action on the part of the consultant. "Results" cannot come from a consultant alone, which Schaffer does go on to say. I don't think a consultant can afford to be held responsible for results, which in most cases are out of her sphere of influence.

What are your thoughts?