The order in which command line options take effect appears to be hard-coded in process_dev, and not the order in which they are specified. Since this isn't documented in the man page, this can be confusing, e.g. the case of trying to set a spindown timeout and immediately going into suspend: hdparm -S60 -y /dev/whatever
The drive enters spindown from the -y, but then the -S60 takes effect and the drive is immediately spun back up.
(Original Ubuntu bug: https://bugs.launchpad.net/ubuntu/+source/hdparm/+bug/221854\)