Valid point but I think what it underscores are the shortcomings of the one size fits all approach to penology. We need a better strategy - one that addresses both the needs of the criminal and the society burdened by the costs of warehousing them for longer than necessary (or alternatively periods that prove not long enough).  

It's all about recidivism - how we get better at evaluating and ameliorating the risk on a case by case basis. Frankly we need better tools - tools which our psychology profession has thus far been unable to deliver.

The key to recidivism when it comes to violent crime is psychopathy. Studies conclude psychopaths are more likely to obtain early release and yet are 2.5 times more likely to re-offend. The absence of remorse is one characteristic of a psychopath and why, hence, it gives parole boards and their advisors so many sleepless nights.