In short, DEs like xfce use the UUID to automatically mount the volume at session startup. The settings are different for each de. The "disks" GUI also has a setting for this, but I haven't seen it since I was playing with mint.

I'm not sure how void would be doing anything differently. I wouldn't rely on the generic device names sda sdb, etc, they change according to how the kernel sees them once they're on the bus and enumerated.

I'm sticking with the UUID theory. As for the corner case I mentioned with the flash drives, it was a bit off topic. And I know not to rely on anything being the same that's hot plugged unless it can be positively identified with a UUID or in the case of DEs, UUID or some fingerprinting scheme.

The configuration settings might be found with udev outside of DEs, but I think you'll find them to be generic in an out of the box installation.

Some DEs look for the device at session start or on insertion by monitoring events coming from dbus or udev. It's not really a specific procedure I trust when dealing with identical models though and the phenomenon might not stand up unless there's some other info being taken into consideration like serial numbers ( something unique to each device ).