I'm making a custom bootable USB flash drive with a persistent partition. Formatting the partition as ext2 obviously makes the filesystem very sensitive to improper unmounting. I remember a while back that Ubuntu (and other distributions) had problems when Flash memory was formatted as ext3/4, writing data so frequently that the flash drives died very quickly.
Have these problems now been resolved? Is there any reason to not use a journalled filesystem when formatting a USB flash drive?
I think that usb drive's every cell has it's own limit number of read/write.
So journaling is not used.
solving this problem may be very difficult.
I use the ext4 file system and turn off journaling in USB drives and memory cards. I also set the mount option 'noatime' in /etc/fstab in an installed system. See these links,
Installation/UEFI-and-BIOS
Pendrive lifetime
Lifespan a flash drive running Ubuntu?
Finally, backup the system or at least your personal data at regular intervals and whenever important data are stored!