Earlier quoted context omitted.
I don't know what the right punishment is for that, but the original sentence of 45 years seems too steep. As does 25.
I agree, but that also depends on the offender. In a way, you could make an argument that prison should not have timed sentences, but rather that it should be "you stay until it is deemed that you will not offend again, and that you can be a productive member of society." After all the word "corrections" implies that something should be corrected, not that somebody should be punished.
If it were only for corrections, then it would cause all kinds of problems. The most obvious one is that you get one "free crime" to commit.
There's also a fairness (and rule-of-law) argument: if two people steal $100 each, why would one person be let out earlier?