Ive heard this does take a while to do, speaking to a guy we did some off raoding with in wales, loaned a bike to a supposed expert!!! went flying into some water and full throttle into the water. Took the guy 2 days to strip the think and replace the dent rod, which in his words was more like an S then a straight line.
I remember near dropping my bike in the water like that, but near burst a blood vessel to ensure it wasnt going under
