I can only relate my experience to east of Buffalo and Harrisburg. I fired and ran most of the NY-Wash and NY- Harrisburg service in the 1970-76 period of PC passenger service. The Broadway Limited Nos 41 and 40 were still run in a first class manner as were the SCL Florida trains and the hands down cleanest The Southern Crescent. Ran the Metroliners and like the Broadway Limited you would never see a slow signal if it could be helped also the Clockers were pretty clean and generally ran on time. The NY Wash corridor was maintained to 120 mph standards and generally quite a smooth ride although most of the interlockings were beat up. The heavy high speed freight traffic beat the hell out of the switch frogs bridging the 6 inch gap in the rail. The SCL trains were called " Big Jobs" by the Pennsy/PC enginmen due to length, sometimes 26-28 cars long and necessitating double stops at the major stations. They were authorized to operate at 100 mph which helped make up lost time.
My Uncle Lou was a PRR engineman and we would ride on his pass over the New York Central from GCT to Rochester NY twice a year to visit his sisters. One lived in Charlotte and the other in Phelps. As an aside he used to take the LV to Geneva out of NY Penn from the 1940's until their trains came off in 61.Number 9 the Black Diamond was his favorite telling me the diner was great and the track in pretty good shape with an 80 mph limit in some spots. He hired out in 1941 and ran the LV trains out of Sunnyside out to NK tower in Newark on occasion.
Riding the NYC from 1965 until 1971we saw the transition to Empire Service. Prior to that most of the trains were long mail passenger trains or long distance intercity trains most of them equipped with diners and sleepers. Time keeping in those years was spotty due to the tremendous volume of freight traffic. It was common place to meet 25 or more freight trains between Hoffmans and Rochester most trips. Those years saw some fierce blizzards but they got you thru maybe a few hours late. One time our E unit died in Utica on Train 71 and they commandeered two U-boats off an eastbound freight and we set out again into the teeth of the storm. The crews were generally professional and seemed to look at the Empire Service as a plus. Most empire trains west of Albany had a snack bar or lounge car in the consist. Many trains operated with 3 to 7 cars and the cars were usually very clean. The track was in good shape except the Mohawk div. which was a real bumpy ride in 65 and 66 they redid that stretch in 1967, and except for the interlocking's the ride was good. The only time I saw really crummy looking cars was Christmas time in 1971 when they stuck 5 MTA cattle cars on the hind end of No. 72 to handle the passenger load. The train became so crowded at Albany Uncle Lou and I got off and rode the trailing E unit down to Harmon and did the same with the electric into GCT. Uncle Lou never owned a car and lived on west 23rd street in Manhattan for 50 years so we hopped in a cab down to the Blarney stone and had a few ice cold ones to release the trail dust. That was my last trip over the ex NYC. Also in 1971 Amtrak was starting to call the shots though most of the execution was done by PC Trainmasters so after this time period commenced it's hard to blame PC for the quality of the service. As Noel stated the train dispatchers and the crews tried to maintain the schedule as best they could in that era and a few bad apples were in the mix for sure.