At a high level, I think it would be silly to say that deterrence is entirely ineffective. I think most individuals making serious arguments against it state that it is only effective in certain circumstances, it has diminishing returns, and as a country, the US errors on the side of sentences which are much longer than necessary.

For example, If a crime is punished with incarceration, it seems unlikely that a person would make a calculated decision that 5 years in prison is an acceptable risk but 10 is not.