I will 'fess up that I actually use Pocket Casts as my main podcatcher and In that I have set up a filter for each podcast with a large back catalogue I am gradually working my way through and then keep new episodes of all my podcasts together in its own filter (I mainly use AP for podcasts where I want access to new episodes ASAP rather than wait for PC to grind its slow gears).
I have been pondering how to do similar if and when PC takes a direction (under new management) that means I want to then move over to using AP as my main podcatcher. At the moment it seems the simplest would be to filter each podcast with a back catalogue by Unplayed and sorted Oldest to Newest.
I wonder if this is the sort of approach that would help you keep on top of your back catalogues?