I want to present the ideas piece-meal (“slowly”) and show how the ideas evolved.
I think that I want something like the opposite of “Merge All Windows” (Mac).
I think that I would like to keep the original board intact, since, for me (not my reader) seeing it all at once generates new ideas and I might want to add more ideas to the main board.
But, I am open to other ideas. I grew up on Windows and Linux. Mac is a different mindset for me. Maybe I just need to do something Mac-like, a Mac idiom, e.g. something that is “obvious” in the Mac culture, but not so obvious to people outside of that culture. Maybe all that I want is multiple views (windows) on the original - one view zoomed into a sub-tree of the board, another view zoomed into another sub-tree and so on.
The only thing I can think of right now is a way to make parceling out the smaller sections easier on yourself. Try this:
Select the first chunk of notes that you want to present together.
Use the Notes ▸ New Background Shape Around Selection menu command.
By default this will be a visually obvious construct, but you could reduce the impact of it by adjusting the border colour, or even removing all visual components entirely and simply remembering that it is there.
When it comes time to export the “slides”, select it.
Use the Edit ▸ Select ▸ Notes Overlapping Selected Shape shortcut (⌃⌘A).
And now you can simply copy and paste into a new board, perhaps first Shift clicking anywhere in the background to remove the shape from the selection.
The only major thing I can think of that might be a shift in how you do things is that you wouldn’t be able to click and drag on the background to draw a selection marquee, you’d need to hold down the Cmd key to avoid simply dragging and dropping the background shape.
It’s not even terribly out of line with what Shapes were made for. If your board is grouped into larger logical areas anyway, it may be beneficial to have them for other purposes beyond easier mass selection.