It seems a shame to have (for instance) a "Succession (British)" and a "Succession UK" castings. Could we either have a mechanism to ask list creators to combine their lists or (probably more practically) a way to create an aggregate casting that takes the results from multiple lists and combines them?

I assume when listing castings you sort them by the number of votes, or something that helps the most popular remain popular, but for medium-popularity lists it seems you can end up with too many. Another feature that might work for this purpose is allowing users to indicate "this casting is like that casting".

Or maybe you just need some work on "are you sure you want to create this casting rather than join one of these similar ones"?

I realise that this is a difficult problem, but I think it'd help the community be more vibrant.