Always worth asking at the airport. It used to be the case of the flight was overbooked / operationally it made sense “flow forward” would be activated and we could offer to move people at the airport early to move to an earlier service.

Now days it seems to have become the “norm” to have flow forward activated on short haul and domestic flights.... (I speak from a LHR perspective) assuming you don’t have “married segment control” applied to your connection.... it’s not worth the headache with that!