I've only got experience with DR2, not 3, but while it can take quite a while I've never had it take more than 2-3 hours for a reasonable sized disk. I also don't remember the progress indicator stalling at any point, although it might have.
Can you hear whether the drive is actually making noise or not? If you can hear it seeking at all, that might indicate that it's doing something (I assume you're booted from a DR disc, so there's no way to open Activity Monitor and check). If the system fans are cranked up to the point they indicate the processor is under heavy load, it could also be working at a processing stage that fails to update the progress bar.
Alternately it could, of course, just be stuck. You'd hate to have it take 12 hours and cancel after 10 because you thought so, though...