I lived in an Asian country and I recently moved to Europe. English was very popular in my country.
I have seen african -american people and British people on youtube ( Mostly african -american) saying " you know what I mean " and " you know what I am saying " in interviews to journalists a lot. This sentence didn't add anything to the talk but just sounds like the speaker is trying to act smart( in my opinion).
This phrase is used many many times.
I accidentaly used it once with one of my professor in an official dinner ( I study at a german university) and he seemed annoyed but didn't said anything. Most people were not pleased and I said sorry to professor after saying this phrase.
Should this phrase be used in informal setting only? I have taken English even at bachelors level and this phrase was never discussed!