systems bunched up close together on the last page

I agree.

Thanks for the more positive attitude!

This is definitely an under-documented area of the program. Here's a page that was fairly recently contributed to the handbook that addresses the topic, although still not completely:

http://musescore.org/en/handbook/layout-and-formatting

Also see the tutorial referenced here:

http://musescore.org/en/node/15668

The way I'd describe it:

The "System distance" setting (Style->Edit General Style->Page) controls the initial amount of space between systems. So in general, if you want more or less space between systems, this is the parameter to adjust. However, the "Page fill threshold" setting on that same page causes all systems on a page to be spread out to fill the page if at least that full. It's a great feature, as it means you don't have to get the system distance set *exactly* to the right value in order to fill the page - just to a value that at least gets the right number of systems to fit on a page. A huge time saver and workflow simplifier. But the downside is, the last page of the score often doesn't reach the page fill threshold, and hence you see the actual result of your system distance setting without the benefit of the cool stretch function.

The way I solve this is to leave the system distance alone, but add a staff spacer below the last staff, then resize that to completely fill out the page. This causes the page fill threshold to be met, thus stretching out the systems on the last page the same as on other pages. The alternative would be to set page fill threshold to 100% and then spent a lot of trial and error time trying to get the system distance just right to fill out the page, but my way is *much* faster.