In fairness, a number of RRBs run and get overtaken by the next train anyway (TFW have one 20:52 off Chester to Manchester Picc and the 21:52 train overtakes the 20:52 bus at Newton Le Willows). For any stations which aren't covered by an overtaking train, in my experience, passengers prefer to wait for the next train if it is only an hour later if the delay is minimal. Therefore, in this instance, the only people who would benefit significantly from this 20:52 bus would be people travelling to stations between and including Chester and Warrington Bank Quay, beyond Bank Quay, it's easier to wait for the next train.
It's all a case by case basis as to whether a RRB should be put on.
Halton Curve is reduced. Should be hourly, but it runs as 2 hourly with the other paths being used for supposedly training but those paths are rarely used. This line is actually used as well, good numbers using the Halton Curve trains.