When will TOCs realise that, unless they have consciously chosen to be tied to a specific train in return for s cheap Advance fare, people do not plan their lives around one particular train? They work late so and so get a later train. They stop and talk to froends and so get a later train. They're having a great day out and so get a later train.
That is flexible, messy, mornal human life. TOCs, it's your job to fit your approaches around that, not for people to put their lives in nice, neat boxes. Deal with it.