Some systems run fsck on every boot, after so many days, or after so many mounts. For example, in How often should I reboot Linux servers? - Server Fault they discuss a variety of strategies for doing so. Why is this necessary? Without some background, it's hard to pick a strategy.
In Marc's Blog: btrfs - Btrfs Tips: Btrfs Scrub and Btrfs Filesystem Repair, the author claims this isn't necessary if you have a
btrfs filesystem, and in Data degradation - Wikipedia they discuss similar self-healing features in
zfs. Perhaps this is an
ext4 specific requirement?
In Drives with Integrity - Designing for Zero Silent Data Corruption Tolerance they imply that cosmic rays aren't a factor when it comes to disks. Could data corrupted in the CPU make it on disk, though, partially explaining the need to run
fsck? Still, I see almost no discussion around
fsck in statistics - Cosmic Rays: what is the probability they will affect a program? - Stack Overflow.