[phossler]

But you have to think:

What are the actual chances of "Mr." or "p." landing at the end of a line?
>95%+ exist within the line

Only a handful are going to land at the very end of a line.
In ebooks, probably more likely, since it'll be read on skinnier devices + larger fonts

but we're still talking about a very small percentage.

All true (esp. the small percentage)

I asked originally because reading on my Kindle there was a

blah blah blah blah blah blah blah blah F. M.
Lastname blah blah blah blah blah blah

construct and it just grated. Once it gets to the Kindle, it's too late unless I edit it again

I prefer ragged right and the Hyphenate PI (again personal preference) so I said,

"Paul, Reg Ex can fix this"

blah blah blah blah blah blah blah blah
F. M. Lastname blah blah blah blah blah blah

Then I saw some

blah blah blah blah blah F. Lastname blah blah blah blah blah blah

and got stuck on the RegEx. The other cases just occurred to me since there was a chance, e.g.

blah blah blah blah blah December
25, 2021 blah blah blah blah blah

All the other cases you mentioned, I most likely won't ever see and will just leave them to the professionals who are working with print