There some guards who seem to avoid walking through the train at all, while there are also some that walk through occasionally meaning if you make a short journey you might not see them walk through and then there are some guards who walk through all the time. I thought the AFCs who occasionally appear are actually spare guards, so they aren't any less qualified. Indeed, once when I was on 2 x 142s it was the AFC who fixed a problem with a set of doors that kept jamming.
And those that seem to avoid walking through the train should be dealt with through the already established procedures for doing so . This has been done to death . I would not defend anybody who constantly sat in the back cab for no good reason .
There is a separate grade of RPA's . These have no safety critical training and are only trained in revenue . They are the people I assumed you meant with the use of term AFC .
I dont know about the depots that work trains you work but for the depots I know there are no longer AFC turns . These used to be turns when a spare guard would go out with revenue equipment and carry out revenue protection duties on double sets comprised of incompatible units. Personally from a service delivery point of view I think it makes more sense to have spare guards sat at depots ready to be utilized to work trains . I have not even seen AFC turns used for guards who are restricted from carrying out safety critical duties either on medical or competence grounds which could be done .
One of the problems with a visibility point of view is when you have a staff member basing themselves where they cannot be seen they are automatically less visible even if they do walk through. Simple solution to that would be to bar staff from the rear cab except under exceptional circumstances e.g. if someone threatens the staff member with violence.
Which is why I would advocate for door controls to be fitted at intermediate doors in the saloon . At least then even when carrying out dispatch duties the conductor will still be visible to people in that carriage. This would make it so much easier for guards to collect revenue on the many lines with unstaffed stations , and remain visible whilst also dispatching the train . Lets face it , its unlikely some of the older stock is going to be converted for DOO . Why not make this step anyway ? it makes sense .On some stock it is impossible to base yourself in a visible location whilst doing the doors , I would like that to change .
I would not disagree with baring use of the back cab apart from in a few situations . When I am working I always try and patrol the train , the only situations that I would return to the back cab would be to fix a fault with my revenue equipment , to contact control / the driver / shift manager , I am being or have been threatened / assaulted or when a train is so overcrowded I could not get through it .