Actually, BlackBrook, even though I agree that they shouldn't have feed 24/7, many people do feed CRX that way.
Being that CRX are a freak of sorts, they come with plenty of issues. What FarmerDan described it sounds like "Flip" but you don't usually see that happening until it gets pretty hot out. They have heart attacks, they have leg problems, those come with having birds bred to their extremes the way these are. I feed once a day so they don't grow so fast, and honestly, they come out just the size I want at 8-weeks, which depends on the strain(hatchery) you are buying from. I get them around 4.5-5.5 and within that range from Stromberg's CRX which are drop shipped from Privet down in NM via TX.
I don't love raising the freaks, but I do enjoy eating them as does my family. I still think that purebreeds give a better flavor to stock and when canned, but for a roaster, I like the CRX.