Well, yes, undoubtedly if you've given away your traffic to trucks and other RR's like EHH has done on the D&H, the couple of trains you still run won't be delayed due to opposing traffic.
Doing away with intermediate classifications is one thing, too, where it makes sense to do it. But the time savings, if they in fact ever materialized with CR, came from the reduction in intermediate classifications- not from the increased train lengths per se- the reduced classification time probably simply made up for the slower trains and increased likelihood of incidents or mechanical failures enroute.
One way or the other, runninga longer train in and of itself doesn't save any time. And while reduced intermediate classification might mean the majority of traffic gets there faster, it also likely means that some customer's traffic either gets bounced around on a lot of duplicate mileage, to eventulally get where its going, big trains have to make more intermeidate p/u's and s/o's, or it takes forever to get spotted. And that will tend to chase traffic away. But from a business sense, yes, your operating ratio may be higher moving less traffic. But Mcdonalds makes a lot of $ selling hamburgers, but cusre doesn't make a super-great hamburger.