I've added a 100mm Macro Lens instead of using a zoom and extension tubes as well as a stack loader which makes it a lot faster loading and unloading slides.
That was 40 slides in about a minute.
Of the couple things we've learned doing this: Keeping the slides in their carousels isn't a good way to store the slides for the long term. If they are in any kind of moist environment the slides can begin to warp and they will jam the feeders of even the carousels they are in.
The stack loader isn't any more forgiving than the carousels for warped slides, those I have to feed in one at a time and they take a lot longer to process.
Storing your slides in something like this can save you a lot of space and aggravation if you care about the slides you are storing.