Only when humanly possible, I fill pages all the way to the end. Rather than changing the leading or blank line heights (which is extremely visible if you have two plain text pages next to eachother), I scan for long paragraphs with either short or very long last lines. Minimally adjusting the tracking (never more than -2 or +10! never in two consecutive paragraphs!) may just "win" or "loose" a line, effectively hiding that extra space at the bottom.
How do I remember what I changed? I don't -- if I get revisions, and a page ends badly, I scan the previous pages for "fixes". Removing them usually wins back the line I lost earlier.
I don't ever attempt to fill more than two lines. Sometimes there is white space at the bottom of a page.