The thought has occurred to me often, that from a finance engineering perspective, using a computer to 90% of its rated CPU cycles would be considered much leaner and more economic than using it to 50% of those cycles. Yet, my "informal" study (I did the research, but didn't write a paper) demonstrated the system was most effective when it was run a 50 to 60 percent capacity.
Since, I have seen many other systems that produce more when not run flat-out all the time. I've often wondered why the transactional managers and finance engineers were never taught that. The only answer I can come up with is that measuring effectiveness is difficult.