What would you want to do? Expand the distance between the staves, so that each page was full top to bottom? How would a conductor follow that? Continue each instrument so that it stayed at the same height, but with random blank spaces between?

i’m not sure there is a good answer.

Not respace staves, resize pages/systems. I've demonstrated it below. Let me know if this makes sense.

That’s a tough one. I think my inclination would be to keep things as consistent as I could. Changing percentages on every page would be (IMO) just asking for a migraine. I assume this is the conductor’s score, and the parts would be individual. As such, I still think I would try to keep it so you would be reading (pretty much) straight across, so that your eye could follow, for example, the bassoon from page to page, and not have to look up or down to find it.

Sorry I can’t give you a magic answer!

Yes, we ended up going with consistency. At first I tried this, and the conductor said, "well, what's the use of hiding the empty staves if we can't make use of all that extra space?" And then I explained that there was no way to automatically expand the page content to fill it, and we both agreed it would take more time than it's worth just so you could see it better. So I just showed all staves and locked 4 bars per system so the bars were always wide and legible.

So it was more just curiosity if a function of this sort existed. It's an interesting concept, if not the most practical or the prettiest one...

I am working on an automatic score balancing plugin for Finale based on Jari Williamsson's JW Lua for Finale.

It will address issues like hidden staves, groups, staff collision, optical spacing and of course the page margins.

Here is a demo of the current version.

https://www.youtube.com/watch?v=SgYjN2FoTNk 

Jan, Elbsound.studio

That would be extremely useful. It could also be relevant to a recent post on the other Finale forum about spacing staves evenly.