Given these numbers, you can keep cranking the knobs but is that really going to be an effective use of money?
At this point, it looks like the only people left are the really hard cases. And they probably need medical and mental health care more than jail.
Whenever I have contact with DUI stuff in the US, about 1/3 are young, idiotic dipshits who did something egregiously stupid and dangerous and wind up on the straight and narrow after being punished. The other 2/3 are so clearly repeat, hardcore alcoholics that desperately need some form of treatment and are so bad that I wonder how they can even function.