I don't think this was purely done for the attention on herself like a typical MBP. BA the "angel of death" prolonged that attention and special position as long as possible by becoming an important person in the grieving parents lives. There seems to be less of that here. Bathing and dressing a baby that has recently died might have been something LL was simply expected to do in her role, rather than signifying much. She also sometimes tried to time the emergencies/deaths for after her shift. If her sole motivation was to enjoy the adrenaline and attention of being involved in the resuscitation then these murders / assaults don't make sense.
Rather, there seems to be an element of her enjoying and relishing the despair and grief of the parents. And her power in making that happen. This is why she made an effort to kill groups of siblings so that there would be no survivors and why she grief stalked the parents afterward.
I have to presume she always "enjoyed" drama and high stakes situations, and being in a position of importance - that's common to a lot of people who work on intensive care settings. Maybe she also enjoyed death and grief, it sort of makes sense for someone who does to pursue work in healthcare, especially intensive high stakes healthcare.
Other NICU staff probably also get a rush and a sense of reward out of navigating high stakes situations, the probably wouldn't seek work there otherwise - the difference is that they are desperately trying to avoid a bad outcome because the parents' despair and grief makes them feel awful, it's an awful thing to witness. And they feel elated and rewarded when their good work keeps babies alive and well. It seems that LL found it more enjoyable when babies died. And she was selfish enough to make that happen.
I don't see this is a mental illness with diminished responsibility at all. She knew what she was doing was wrong and caused suffering - she wanted to observe the suffering and privately revelled in it. She conducted her life outside from these murders / assaults in a normal and relatively functional way. And she wrote notes indicating he understanding that her actions were evil. Quite apart from the poor babies and their devastated families she also inflicted this on her colleagues. People she pretended to be friends with. They would have suffered immeasurably also. From the pattern of her behaviour she probably enjoyed their distress. I have no sympathy for her. Whatever caused her to develop as she did, it seems that this is who she is at her core. An appallingly cruel, sly and selfish person.