Bro? Never.
I do use "dude" and "man", but only in very specific circumstances and only with friends and close acquaintances... generally, I use "dude" or "man" in admonishing sentences to make them seem a little less harsh or unfriendly. Oh, and sometimes I'll use "that dude" if I'm bored with "that guy". It largely depends on how I'm feeling and I typically only use it if I'm fairly relaxed. I also tend to use "man" if I'm feeling exasperated. "We're having this conversation again? Come on, man, move on."
I only started using "dude" in the past couple years. I have no idea why.