Regarding the issue of short and long trains, there was a time, decades ago, when the trains on our subway system ran short 4-car (rather than 6-car) trains in the evening, after rush hour. Sadly, we are no longer able to sit or stand at the very front of trains and look at the tracks during travel. But I used to see big black signs below track level, for the benefit of drivers, with a white number "4" or "6" printed on it. The "6" was always at the far end of the train, meaning a full 6 car train is to stop there. The "4" sign could be next to the "6" sign, if short trains are to stop at the far end of the station, or they may be a hundred feet back if the train is to stop at the end of the station where they came in. Even though these signs are long obsolete, they were still there last time we were allowed to look out the front of a moving train, pre covid, and they may still be there, at least on line 2.
Similar to what was said in a post above, when standing on the plaform waiting for a train, I used to get annoyed when a short train either went past me, or stopped short of where I was standing, so I had to run to catch it. I wished they would put up signs telling the public that the end of trains may not go past a certain point on the platform in evenings, rather than having hidden signs just for drivers.
So if they are going to run short trains again, I hope they put up signs warning which parts of the platforms may be beyond the end of a short train. To paraphrase a quote from Dr. Strangelove, "Why didn't you tell us?" "We were saving it for a surprise!"