[Aaron]

I don't brake check at all. In fact, I cringe when I have to brake hard that the person behind me might not make it.
However, I had a friend once whose car was beat up and not worth repairing. He would brake check for real. In other words, he didn't just tap to scare you, he waited for you to get close enough so he could nail the brakes and have you total his car. When you're following close enough, you can't discount the deer/dog/cat/child that ran in front of the car while you were rear ending them. Just a warning for those that follow closer than normal...