If you're tempted to skip the second stage, image verification, you may not find out that you've lost images until it's too late to do anything about it. Whenever possible (with the full recognition that it isn't always possible), I don't touch an image until I know that I have two good copies that aren't resident on the camera media. I may be paranoid, but I've yet to lose a single image! If you allow Bridge to verify the images before you reformat the camera media, you'll have a chance of recovering your images if something goes awry in the ingestion phase. If you shoot new images over the old ones and the copies are bad, those images are gone forever.