[marhutchy]

Is it possible to have Kodi read from one folder just for actors/actresses images?

No, not currently possible.

However, isn't it redundant?

Yes, the current solution is massively redundant and inefficient. A single cast folder for local cast artwork across all movies (even tv shows) would be much more efficient, but also more complicated (what to do if you have multiple sources - share cast artwork across sources, or have one cast artwork folder per source, maybe in the root of each source?)

As usual it needs someone that is bothered enough by this to improve it, and in the grand scheme of things it's probably way down most peoples lists of priorities. At least it works, even if it is inefficient...

That is true.
That's one of the reasons why I had second thoughts about asking, because I know it isn't a major issue - it isn't prioritized.

For multiple sources, I would suggest the same method that Movie Set Artwork Automator addon uses.

Thanks for responding