I'm all ears, and recommendations?
Fortunately we have moved beyond the sending by using OneDrive - which is great when working. It is just the replicating and merging.

By versions, I am referring to versions of the product not the slides, but the slides reflect the product. And because of agile, lots of releases! So a slide (might be updated slide or a net new slide) with details about a future release will exist in advance, but should not be published until date X or release Y.

Oh, what about when a slide is common to multiple decks? E.g. a big deck and a small deck. It would be nice if updating the master trickled down to the dependent decks.