New Apple security feature reboots iPhones after 3 days, researchers confirm

Periodic reboots are actually a PCI requirement for payment terminals heh, basically every point of sale on the market reboots every 24h.

Seems like a good defence in depth strategy. These days most systems have a pretty good boot chain security, so after a reboot you know the system is in a valid state and any potential malicious changes have been flushed out.