What is the difference between the following two sentences? She goes to the forest three times per week. She goes to the forest three times a week.
meaning - Difference between "per" and "a" - English Language & Usage ...
I certainly don't prefer per or even as per @kris. The stated examples of use given by the OP are obscure and indistinct statements so weak of meaning that I suspect they are not used by a native speaker with any depth of experience or culture. Lewis Goudy's answer is the most relevant response here. Everyone else seems to just be stating their personal preferences for weak modern usage with ...
Use of 'as per' vs 'per' - English Language & Usage Stack Exchange
The particular construction as per my knowledge is unnatural - as per is normally only used in reference to some prior statement / school of thought. It more properly corresponds to in accordance with, and can't simply be used to replace the idiomatic according to my knowledge / information / understanding.
The room costs 40 € per person. In this case, per has a meaning for for each. This matches with the main question as asked in the topic title, but doesn't with the example given in the thread itself: per John, as you never charge something per John, haha. There's another case where per would fit both your examples. Like this:
meaning - What does "Per [person's name]" mean? - English Language ...
"per" generally means an averaging. One may study for 5 hours one week, and 15 the next, and achieve 10 hours per week. "each" generally means either an equal distribution, or a minimum, or both. Studying 10 hours each week would mean at least 10 hours every week.