with the expectation that there was parole and that the parole board would consider them for release after a certain number of years and that many / most people served only a portion of their sentence because they were granted parole.

The judges and prosecutors certainty knew that and had a pretty reasonable understand of how long someone might actually serve with a 30 year or 50 year or life sentence. A jury might not have known quite as well, but most people knew about the parole system and that those convicted would likely serve well less time than the sentenced given.

Judges would have taken this into consideration when giving sentences, prosecutors would have taken this into consideration when seeking / recommending sentences. Convicts would have taken this into consideration when taking plea deals.

When Virginia eliminated parole going forward, it appears that the whole attitude toward parole changed and the parole board became much much more stingy. A judge gave a life sentence and prosecutor who recommended a life sentence both probably did so with a understanding that person would likely be out in 25 years with solid behavior. Same with a 40 year sentence, etc. Then after the change, those people are not being granted parole in that time frame.

I think the system we have now is much better - sentence them to what they get and you know exactly what to expect. No guessing if the judge really thought he should serve 35 years or if the judge sentences him to 35 years expecting that he would get out in 15. But for those still eligible for parole, it is reasonable to assume that when they were convicted and sentences, the justice system overall didn't actually expect them to serve all or even most of that sentence.

Obviously, we are talking about 20-30 + year old cases at this point and many of those involved can't remember, are dead or are just no around.