Anyone who gets a license is taught how serious of an offense it is and how dire the consequences can be. A person who disregards that isn't fit to drive and, in my opinion, needs to spend some time behind bars to let it sink in.
The guy who killed my brother got about 2 years and my understanding is that he turned his life around after his incarceration.
and I wonder if my brother would still be alive if the guy had been locked up for a handful of months before his final DUI charge.