For most incidents, the prosecution was relying on eyewitness evidence from people who were very much in the room. So while they worked to identify moments when Lucy Letby could have been alone with babies, they wouldn't claim she was alone at many of these times. And evidence from consultants, doctors, nurses etc says she wasn't alone, in many cases.
The children were supposed to have one to one nursing in the NICU cots, so you could have four nurses in nursery 1, including a shift leader, and it would still be understaffed, on the busiest nights. Staffing on the nights we know about tended to be lower than that, but Lucy Letby wasn't working alone all night all the same.
She may have been alone with baby K. I certainly wouldn't deny that she would be alone with babies sometimes. That was an occupational hazard. But the prosecution has exaggerated the pattern here all the same.
The case for baby K is a particularly shaky one - the idea that Lucy Letby was alone in the room depended on swipe card data showing that Caroline Oakley, who was in charge of two babies there, left the unit 20 minutes before the alleged attack. But that's the swipe card data they mixed up. That's when Caroline Oakley came back in.
She says, reasonably enough, like Lucy Letby, that she remembers nothing about that night. Joanne Williams, who was the baby's designated nurse, does have memories - of Dr Jayaram asking her who was there when the child desaturated. (She wasn't, so couldn't say). So if we are relying on Dr Jayaram's memory alone now to suggest Lucy Letby was alone on that ward, it's not looking very reliable.