Some years ago (I think it was when the 357s were being introduced on the C2C route) there was a TOC official who gave a presentation about the new trains and he said that he preferred multiple unit trains that are not fully walk-through between the units because some passengers might walk through the train to be at the correct portion for the exit at their destination station.
OK, so I understand about trains sometimes being very crowded at some portions (could be the middle, or an end) and having empty seats elsewhere, but I took exception to a railway industry official actively working to thwart a capability because the passengers like and benefit from it. In those days no trains had LCD displays with indicators showing seat occupancy levels of each carriage (a feature that - unless I am mistaken - is still sorely missing from all trains built by Bombardier / Alstom).
Normally I walk along a platform before boarding a train so that I will be at the correct exit location but if the train is already at the station I will board it and then during the journey move forwards / backwards, as required.
There have been times when I have walked through an entire 9 coach Elizabeth line train just so that I can be at the right location for the platform exit at my destination station.
I cannot do this on the Central line (for many reasons, including my own safety, I will not use the emergency door) so at stations I walk from car to car or run along the platform, passing several tube cars on the way. Then during the journey I walk through the inside of the car so as to be ready to repeat the routine at the next station.
btw, when I created a website about transport I included a page on the topic of train end cab designs / walk-through capability. Apart from the copyright year most pages on the website have not been updated for many years but as a general theme the core information is still valid.
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