Ever since I bought my Canon T1i/500D a little over a year ago, I've gotten in the habit of shooting both JPG and RAW for every shot. My reasoning was so that if I got a really good shot, I'd have a high quality RAW image as a back up to tweak and process to make the shot nicer, or fix something if necessary. I rarely ever found a need to process a RAW image, even for shots that I consider to be really good shots.
For a short time, I turned off the RAW format and shot only JPG. More shots per SD card.I turned RAW back on when we went on our recent family vacation to Toronto and I'm really glad I did. I had a few "accidents" and shot images with totally messed up white balance, and even a few with the wrong aperture/shutter speed, resulting in an underexposed image. This afternoon I decided to finally start digging through all of the photos I shot on our trip. I'm amazed and how much I was able to fix the underexposed images using the Canon Digital Photo Professional software that came with the camera. They're far from perfect, but they're better than a wasted shot and they turned out better than any underexposed JPG version of the same photo using a few tools that I often use for such things. Not only that, but I started changing the white balance for a few seemingly good shots and found that they looked even better. Most of the time, I had my camera's white balance set to Auto. It does a pretty good job, but I noticed differences between an "auto" photo shot outdoors, compared to a "daylight" photo shot outdoors. You'd think they were the same, but that's not the case. The same applies to indoor shots with different lighting. Coincidentally, I'm currently reading "Light Science & Magic" and it talks about the fact that sometimes lighting is a mix of different light sources, which can result in incorrect colour. It's cool that I got to see the practical side of that first hand. Anyhow, rather than hunt and peck through my images, I decided to do them all. All 633 images. It took me most of the day, but I'm really happy with the results. As I write this, DPP is exporting all of my processed images back out to JPG versions that I store on my PC. The original RAW files will remain on the 1TB external drive. After this experience, I'm almost tempted to turn off JPG altogether and shoot just RAW. Almost. There are times that I do have a need to shoot a quick JPG and really don't have a need for a RAW file, so I think I may end up keeping it on for now. I may turned off JPG for future trips though.