I think when it comes to things like Lois'/Lois's we often tend to forget that, just like everything else, grammar and punctuation evolve. Nothing stays the same. Fashions come and go with this as with anything.
I've mentioned before in the past during such discussions that I was unfortunate enough to be taught grammar and punctuation at a time in the sixties when some pretty radical ideas and education experiments were going on.
The idea then was that in ten years we would no longer be writing, we would all be typing. (Yeah, I can't believe that one flew either) Writing would be obsolete. So what was needed was a form of punctuation and grammar which would save typing time. Brilliant plan, huh?
Much in the same way that language was adjusted to cut down time when doing shorthand. Same idea.
As a result - just one small example of the madness - I was taught to ignore the difference between it's and its - yeah, cut out that apostrophe, that'll save a couple of seconds.
It took me a long time after leaving school to figure out what the difference
was and even then much longer to actually do it, since the habit of leaving it out was ingrained in me by then and I was always forgetting. For years I would type something and then have to go back and remember to insert the apostrophe where appropriate.
That's an extreme example of course, but it does illustrate that we're often at the mercy of the 'experts' in deciding what's right and what's not. And that probably in part explains discrepancies like your various grammar guides, Lynn.
LabRat
