For much:
An understanding of a sentence - much + adverb
Is "very much" an adverb or an adjective?
But it still doesn't explain how "much" as an adverb, can be used or not used.
It read that you would say "You worry too much", but not "You worry much".
Not being used alone with a verb.
It's said here:
Warning: We don’t use much in affirmative clauses:
I hadn’t seen my mother for a month. I’d missed her a lot.
Not: … I’d missed her much.We use much in questions and negative clauses to talk about degrees of something. We put it in end position:
I don’t like the sea much.
I've found this in many other forums/sites:
https://forum.wordreference.com/threads/i-work-a-lot-but-not-i-work-much.2892135/
People just don't use "much" in positive statements, Madagascar. I'm not sure there is any special reason for this practice, but grammar rules are often arbitrary. You certainly have the right idea about when and when not to use "much".
I'm really surprised, because I've heard many native English speakers that don't know this rule.
So, is this rule applied only by Cambridge?