The more outs you have, the better numbers you get. My job, to get the best number. I am not comfortable with any less than 20. And yes, I cycle some through to get some bonuses. The good ones I keep, the bad ones I dump. Very similar to tax free munis. Of course I am loaded with the AAA books. They always stay. But there are only so many of them. Then you start getting into BB books, maybe a wart or two, but still able to work, very little risk. Once you start playing the C's, you are gambling in more ways than one. Of course when going with 20+ books, they have to be trouble free, and operate like a fine tuned machine. When one presents headaches, worse yet, consumes all of your time, I have to cut them loose. I will not venture into junk books, known bad history. Take a flier on a newer one once in awhile, I started with Pinny when they were questionable and new. But if you were limited, I would never stray from the top proven books.