In the past, if a customer has a suspect network or if the app is subject to timing out due to latency (i.e. Remote Desktop, etc.), then I turn CAM on.
Also, if the customer uses good practices for battery charging of their mobile devices I might turn CAM on from the beginning and maybe adjust back to Fast Power Save if they start noticing battery issues.
The only time I have found that CAM mode helps is when the APs do not play well with the power saving schemes on the device. CAM mode is a good test if you are having network issues. If it fixes a problem, it's worth investigating to find out why. There may be some AP settings or firmware updates for the APs or the device that might make power saving mode work properly. I try not to use CAM mode in production unless it is the only way to make things work.