Studies have shown that extremely harsh penalties have minimal deterrence effects compared to moderately harsh penalties. More specifically, they advocate for a response function with a gradually decreasing gradient. Unfortunately, they have no recommendations as to what makes for a "moderately harsh" penalty, and they even acknowledge that some studies have shown deterrence effects from policies such as California's 3-strikes law.
https://www.nap.edu/read/18613/chapter/7#132
Studies have shown that extremely harsh penalties have minimal deterrence effects compared to moderately harsh penalties. More specifically, they advocate for a response function with a gradually decreasing gradient. Unfortunately, they have no recommendations as to what makes for a "moderately harsh" penalty, and they even acknowledge that some studies have shown deterrence effects from policies such as California's 3-strikes law.