Rules will vary from state to state in the US, but yes, if she wants to get out she will have to figure out what the Parole Board wants to see from her, and do those things over the 15+ years she will be in prison. But even then, the nature of her crime (and any statements the victims families will choose to give) will factor in. It would not surprise me at all if the parole board just issues blanket denials to the first applications for murder convictions.
And yes, like all systems, it has been abused in the past, but some states seem to be trying to improve it. There is no uniform set of qualifications to serve on these boards, and I bet some states pad the board with rhe Governor’s friends. According to the Wiki article on parole boards, though, some states mandate that at least one ex-convict needs to be on the board.