Download/write speed very slow

[robotuin]

just deleted "sync" in /etc/usbmount/usbmount.conf
on the line MOUNTOPTIONS="sync,noexec,nodev,noatime,nodiratime,rw"
and I got a nice performance boost of roughly 2MB/s more on network transfers that way

no I was wondering:
somewhere else I read that I would have to manually sync the device before unplugging it,
but if it's constantly connected, wouldn't it automatically sync on shutdown?

thanks in advance!