To be honest there’s no golden rule. I think when you consistently (there are always good exceptions to the rule) create single sentence notes you’re probably not doing it right and should try to group things more per topic/subject. Likewise if you add each week’s meeting to single every growing note you’re also taking it to far and should think about splitting things up.
I’ve just written some more on this topic here, perhaps that helps getting a better idea:
Likewise, this topic contains perhaps some more visual examples of how to chop things up in the right bite size: