There are a lot of long threads on this, so I understand that you might have missed it, but people have actually answered the question about why the deaths and collapses followed her from night to day a few times.
I've answered a few times myself so will just copy over a useful answer I've seen on Reddit this time:
They didn't.
There are two categories to think about, deaths and collapses. Collapses were never well defined. The police, guided by Dewi Evans, started by identifying collapses on day and night shifts for all of the period in question as suspicious. Then they removed the ones Lucy Letby hadn't been present for. Now it looks as if collapses followed her from nights to days.
^See: https://www.reddit.com/r/LucyLetbyTrials/s/dC2XaDGgYU^
Deaths are not so difficult to define. Among Lucy Letby's convictions, we get five deaths at night between June and November 2015, and then two deaths by day in June 2016. Lucy Letby moves mostly to day shifts in March 2016. In the meantime, there have been 2 deaths by day and two by night between September 2015 and March 2016, as well as two for which we don't know times. So deaths are clearly not following her from night to day.
The unit does seem to see more deaths at night, and Lucy Letby is usually on shift at night. It's not surprising that babies were more likely to die at night, since there were fewer senior staff at hand and longer delays before on call consultants could be present. For baby C, who had a difficult and delayed resuscitation, a consultant would have been cotside within five minutes by day; over twenty that night. For baby E, a consultant would surely have given a blood transfusion, but the registrar on duty failed to do so.
Any nurse working night shifts risked being present for more deaths, especially one of Lucy Letby's rank and qualifications, since she was senior enough to care for ICU children but not to manage the shift.
So, not a question of deaths and collapses following Lucy Letby. A mixture of selection bias (collapses) and predictable pattern (deaths).
https://www.reddit.com/r/LucyLetbyTrials/s/9cUPNAYOqO
Lies, damned lies and statistics, as they say