RAW or JPEG? Which one when?

1: Are you shooting in auto mode and just selecting raw as the output?!?!?!? You should definitely be able to adjust all settings needed for a good capture on the fly.

2: If your settings for the camera ... focus, white balance, aperture, shutter and iso are all correct there is nothing that can go wrong other than poor software and really there hasn't been an article to date which says everything went wrong in a cameras software algorithms. We can absolutely make errors in judgement BUT lets say your focus is wrong, aperture, shutter ... raw isn't going to help with these regardless.

Let me also say that while raw can be used for the ultimate improvement, it can also be the ultimate failure if the person doing the editing doesn't know what they are doing. I have seen plenty of images from people over sharpening images, using too much NR, creating posterization, getting the WB wrong because of an uncalibrated monitor. RAW is not the end all, it never will be but I agree it is the ultimate way to "potentially" create the ultimate image. But it will not be the cameras fault if ultimately you fail to realize that potential.