This is a straight out question about money and how much is too...

This is a straight out question about money and how much is too much in the hands of just one broker? I have a full time trading friend who has his money split across a half dozen brokers. He believes too much money in the hands of one broker captures unnecessary attention and is risky (eg the broker goes bust). For those willing to share, I'm interested to know who uses multiple brokers and get a bit of an idea of thresholds at which one might consider opening a 2nd or 3rd account elsewhere.