Can you predict a verdict by how long the Jury deliberates?
In my experience, you can never guess what a Jury is going to do. You can only hope they see your case your way. The conventional wisdom is that longer deliberations favor the prosecution. This is because, typically, the Defense has asked the Jury to just throw the case out, i.e. find "Not Guilty" and we all go home. Therefore, if the jury is spending time deliberating, they have rejected the option to throw out the case and go home.
However, the conventional wisdom is not applicable when there is an insanity defense. The jury is not asked to simply throw the case out of Court. It is asked to evaluate complex expert testimony and evidence and determine whether, in this case, Hemy Neuman, lacked the capacity to know right from wrong at the time he shot Rusty Sneiderman. This is a complex analysis for any jury to complete.
So, in this case, the Prosecution has asked the Jury to forgo the long complex analysis regarding the insanity defense, and just find Hemy Neuman guilty. Longer deliberatoins, therefore, would indicate that the Jury is taking Hemy Neuman's mental illness seriously, and will likely determine (a) if he was in fact bipolar with psychoses and dilusions and (b) if the mental illness was so severe that it caused Hemy Neuman to lack the capacity to know right from wrong at the time of the murder.
Even going through this analysis, the Jury could answer "Yes" to (a), but "No" to (b), and the result would be Guilty but mentally ill.
In this case, I would only feel confident concluding that longer deliberations mean that the jury is taking their job seriously, and is giving attention to Hemy Neuman's mental state. It cannot be said that longer deliberations, however, favor either side in this case.