The reduction of prison sentences is not a mathematical formula that can be computed separate and isolated from other factors that must be considered.  

It is not an estimation solely driven by the mechanical subtraction of years from the sentence. There are qualitative considerations like good behaviour or if the inmate, by his actions, had exhibited true remorse and rehabilitation.    

If the person had committed a crime while in prison, like stashing shabu inside the statue of the Blessed Virgin Mary, does this not affect his chances of clemency or even forfeits it?

In his ledger of sins, does the commission of a new crime cancel whatever penalty was extinguished by previous good conduct?   

Does the new law cited by the DOJ  exempt “recidivists, habitual delinquents, escapees and persons charged with heinous crimes" from its coverage or does it take the likes of Sanchez from its purview?

Lastly, in the grant of clemency, should the friends and family of the victims be mandatorily consulted , and in fact, as the ones directly suffering from the loss, be the first to be solicited of their views, and should the latter be given much weight?