Using microtype (or similar) to sequeeze/extend paragraph by one line?

I am tuning page breaks for a book; it has very short paragraphs (dialogues), many 2 & 3-liners, thus many potential widows/clubs which I try to avoid; this leads to large stretching of vertical space, which I would also like to avoid.

I can improve the page break in individual cases by making a paragraph one line shorter (sometimes only one word which I need to get rid of), which currently involves a reformulation or omission (and communication with translators).

Could I use microtype (which I already use) or some similar "invisible" and textually non-invasive technique to change (i.e. make TeX more likely to choose) the number of lines for a paragraph in individual cases?

`````` looseness=-1
immediately before the paragraph TeX will try to make one less line. (With other positive or negative numbers having the obvious effect. The line breaking still has to meet the other limits of `\tolerance` so this will only have an effect if there is a "reasonable" choice for line breaking with a different number of lines.
The `\looseness` register is always reset after the paragraph so only affects one paragraph.
• I've wondered before about what the value of `\tolerance` should be, and whether one should tweak it. Could you add something about this? – Sverre Jun 7 '17 at 10:45