With respect to that specific question, it has to be remembered that there is no discretion on a first-degree murder sentence. It's a life sentence. The eligibility for parole is set at 25 years.
A murder trial itself can take weeks and months; the sentencing takes five minutes, literally. It's pronounced, often even though there's no discretion on the judge's part at that point. Victim impact statements are received, because they will follow the offender through the correctional system throughout his or her history and will be used when it comes time for parole hearings and other interim release options.
The simple answer to a straightforward question is that I believe not, even in those cases of second-degree murder in which there is some discretion between life 10 and up to life 25. What the judges are reviewing at that point are the circumstances of the offence itself, including the degree of gratuitous violence and the circumstances surrounding the actual act. This is not an exhaustive list; there's a whole slew of factors that go into reviewing what will be set as--