Does anyone know how I can space out systems evenly on a page, so that I don't wind up with a lot of white space at the bottom of pages that don't fill up with systems?
There is no elegant way of doing this in Notion. But here's a labor-intensive and not very flexible work-around: Imagine a 2-staff system. To add space between the staves, press shortcut key "k" to get a text block, either below the top staff or above the bottom staff. You can leave the box as is by clicking somewhere outside it (it'll leave a piece of text that reads, "Text"). Move the word Text vertically until it has given you the desired space between the staves, then doubleclick on the word and change "Text" to a space.
Drawbacks:
— It takes forever, and you probably would use this only as a last resort.
— On a page with more than a handful of staves, it would not be worth anyone's time.
— I haven't been able to select the [space] text item after I created it. If you want to make sure you can get to it again, to make adjustments, type something really small but visible, like a period.
P.S.: I've just posted a feature request that deals with related issues, under the subject "More options for titles, etc."