"Man sieht, wie lange sie unterwegs sind."
Is "man sieht" commonly used in the same way as the english "you see"? Does one not say "du siehst/ ihr seht, wie lange....", OR is "man sieht" really used so often and to cover any general appeal to the company's attention. NT. I can understand the german "man sieht" here, as elsewhere, as used in the 'impersonal' sense - just as the english 'one sees', but I'm wondering whether it is used in the more personal/direct sense as in the english 'you see'...
"Man" is impersonal and is much more common than "one" in English. The same meaning is often conveyed with "you" in English, but you should not use "man" if you want to address a specific person, you'd rather use "du" or "Sie".
"You should not use" - see that again? This phrase of mine will be likely translated with "man" in German or "on" in French or an impersonal phrase in Russian because it is more likely addressed to everyone who is reading than to you alone.