It's impossible for doctors and nurses to pass on everything they know about a patient during shift changes, which can be seen in the form of spikes in deaths and other bad outcomes right after care is handed over to a new team. Hence why they tend to do longer shifts.

That effect is eventually balanced out by exhaustion, sleep deprivation, etc taking the same toll they do on everyone. Theoretically If you could reduce the impact of sleep deprivation, we could push shift lengths further, reduce the amount of turnover in carers a patient sees even more, and receive even further benefits in health outcomes.