I'd have to disagree. First with the very notion that rail infrastructure should be ripped out when traffic is down, with little consideration for future traffic potential, as Conrail in many instances did. By this sort of logic, it would have been "efficient" for the Santa Fe to rip up its second main track in most places on its Chicago to Los Angeles main line in the 1980s, which (like much of the infrastructure destruction done by Conrail in pursuit of the "efficiencies" you speak of) would have been short-sighted and stupid. Second, with the notion that the northeast should have been placed under a single railroad without any rail competition, such that the incentive was always going to be to tear up as much infrastructure as possible in order to prevent any competitor from gaining entrance to the market to disrupt its monopoly, all while ignoring the long term issue of the likelihood of additional rail mergers, none of which could be permitted to allow any single carrier to acquire an "exclusive" on northeast rail traffic (so at some point, the northeast "spoils" were going to be divided up, and they should have ensured that was considered in the "plan").
You have to remember that when NS got the "PRR" side of Conrail and CSX got the "NYC" side, there wasn't enough left (of the ex-PRR and ex-NYC routes) for either of them to get what they needed, and a good deal of "capacity improvements" (read: re-installation of capacity Conrail should never have removed, or addition of capacity Conrail should have added itself, but was incentivized NOT to by virtue of it being granted a monopoly over rail traffic into the northeast) were necessitated both within a short period of time after the sale to NS/CSX, and continuing to this day, due to the "capacity" issues caused by the excessive removal of northeast rail infrastructure by Conrail.
For example, since Conrail ripped up/downgraded the ex-PRR "Fort Wayne" Pittsburgh to Chicago line from a two main track, CTC 70mph (for freight) main line to a single track, unsignaled, inadequately maintained line west of Crestline, OH, NS had to take a significant chunk of the "NYC" side from Cleveland to Chicago, and thereby require a longer route vs. the original ex-PRR (i.e., the Conrail routing for such traffic due to its cuts), while CSX was forced to swing its traffic off the ex-NYC at Cleveland, OH and dip down to Willard, OH to connect with and use its own ex-B&O, which required significant re-installation of a second main track to handle CSX's anticipated new traffic, also adding distance vs. the original ex-NYC route directly west from Cleveland through Toledo. So due to the excessive tearing up of infrastructure by Conrail, BOTH CSX and NS ended up with routes between NYC and Chicago that were both longer and slower than the original NYC and PRR routes. CSX also needed to upgrade the former NYC "Water Level Route" east of Cleveland to 70mph from Conrail's 60mph maximum in order to be able to establish schedules satisfactory for the coveted UPS traffic given its longer/slower Chicago-NYC (northern NJ) route compared with Conrail's routes, and has further needed to add a good deal of new passing sidings and additional main track on the former NYC "West Shore" or "River Line" between Selkirk and the northern NJ terminals, since Conrail once again didn't need to concern itself with speed when no rail competition existed for its traffic base. Oh, and NS has been working on upgrades to its portion of the ex-PRR Fort Wayne line, because the ex-NYC line from Cleveland to Chicago is now clogged with trains, another fine confirmation of Conrail's cuts having gone "too deep."
Another prime example was the ripping up of main track No. 1 on the ex-LV between the "Potter" interlocking in Edison, NJ and Port Reading Junction in Manville, NJ, as Conrail was moving its high priority MAIL, TV, and ML trains, and its symbol "manifest" trains, from the ex-PRR "corridor" (now owned by Amtrak) onto the ex-LV and ex-RDG between Harrisburg, PA and the northern NJ terminals (NYC metro market), plus its southeast to northeast traffic from southern connections. Even the Lehigh Valley, running a comparative handful of freights each day, didn't rip up the infrastructure to that extent. The key difference being that the LV had to compete for rail traffic, and Conrail did not. 20 years after Conrail ripped up Main 1, CSX and NS had it rebuilt to deal with the congestion caused by this short-sighted and stupid decision. If two competing railroads based on the ex-NYC and ex-PRR were established instead of the "all in one" Conrail, the railroad with the ex-PRR side would have been adding second main everywhere it didn't already exist between the northern NJ terminals and Harrisburg when it was pushed off of the "corridor" by Amtrak's user fees, to allow it to attempt to beat its competitor's service. Ditto for the holder of the ex-NYC side adding "River Line" capacity between the northern NJ terminals and Selkirk.
Now don't get me wrong, I understand that Conrail did what was best for Conrail in terms of its infrastructure trimming. But that's the whole issue. Conrail, given a monopoly on northeast rail traffic, had the incentive to preserve only a "minimalist" system, since it (A) didn't need to compete for speed or service level with any other railroad, and (B) had the incentive to ensure no competitor could enter the region and break up its monopoly by ripping up anything another railroad might be able to use to "invade" its exclusive territory. If the USRA planners did things the right way (which would have been a "dual system" plan from the start, and NOT based on pitting some "also ran" system against essentially the PC), they would have preserved more of the northeast's rail infrastructure and we would have a better rail system in the region today than we do. Conrail's "rationalizations" absolutely resulted in too little infrastructure and slower speeds (than NYC and PRR and, for that matter, the EL and (according to some) even the LV (via N&W connection to Chicago) in certain areas) used to provide - due to too much mainline consolidation, too much conversion of controlled sidings to non-controlled sidings in multiple track main line areas, and too much single tracking of multiple track main lines and junctions. A good deal of which Conrail's successors have had to spend a bundle "correcting."
GE, not EMD, makes the best locomotives now; has for over 30 years. Get over it.