Is there any way to upload a collection, then share it all at once?
I don’t think so. You have to upload text and audio for each lesson, so I assume that’s why you can’t “batch upload”, or “batch share”.
It would be really convenient, though.
Clicking on “Share this item” doesn’t take too much extra time, but what if the tool enabled you too import audio and text at the same time (assuming both files had identical names), automatically identifying a “header 1” (from Word) as the title etc. Then you just had too check the boxes of those lessons you wanted to share… 
I agree it would be nice but you can’t do this now.
I’m just thinking aloud. 
It’s not a big issue for me, because mostly I have to edit (at least have a second or third look at) the content anyway, and as I said - clicking on “Share this item” doesn’t take long.
Well, I asked because I have some large collections, and it’s impossible to upload them all at once, and I wanted to introduce them to the library when they are complete.
I don’t see why you wouldn’t upload them one part at a time. Nobody is likely to study the whole collection all at once. It takes people some time to work through each part or lesson.