Today I started an English course with a new teacher. After being asked to arrange words into a proper sentence, she pointed me out on being wrong on something: I said "tomorrow at six", and she said that i should always say "at six tomorrow". I questioned why, and her answer was that the order of adverbs of a single type should be the specificity. The same rule would apply to "In my living room on the couch", where it would be incorrect and the correct form would be "On the couch in my living room". Another example where I would be wrong would be something along the lines of "Next week on Friday at six", the correct form would be "At six on Friday next week", no other forms would be correct.
I had never heard of this rule before despite using both ways quite often. Our English teaching material also showed this and explicitly said it's a rule, however i could not find a single mention of this outside of our specific material, and after asking around from some British friends, they said that the rule was nonsense. I would like a clear answer on this and if possible, something to cite as well.
I had a previous English teacher who i proved wrong on some conditional stuff that she was teaching wrong before as well, the quality control around here is not the greatest, though if I am wrong then please point me out on it, I want to learn. Is this an actual rule, just preference, or completely nonsense? Any help would be appreciated.
Edit: I appreciate the linking of https://www.thefreedictionary.com/Order-of-Adverbs.htm, which cites the same information as present in our material. However this seems less like a set in stone rule and more like a rule of thumb for when in doubt. Am I correct on this? Again i can't find anything about this in stuff like https://www.uop.edu.jo/download/research/members/oxford_guide_to_english_grammar.pdf. Thanks!
Edit2: In the examples given in the aforementioned link using other arrangements sounds unnatural as well, which would be understandable. However there are a lot of cases where both seem just fine, at least to me.