Good point, although it probably won't be 4 for most labs, perhaps 2. My gf does 1 nightshift a week and she is alone in the lab for the 3-4 emergency samples that come in (versus a team of people processing hundreds during the day), there simply isn't much demand at night. Most blood sampling has a human pipeline of people going to their doctor or hospital with an issue, getting blood taken, which is sent to a lab, the majority of that during the day.

Again for large scale centralised labs that get sent samples throughout the 24 hour period from all across the world, where timing isn't an big issue, this could work. But most labs are small, close to the customer, time-sensitive, and work with couriers to bring samples because samples need to be transported and stored in specific ways not to go bad.

She works quite long shifts btw (10-12h), but that's more a function of her country/company culture rather than the norm. Probably 6-8 is more common indeed.

6? Not 8?