cool smartd trick that people don't seem to be widely aware of is that you can schedule scans in smartd.conf: DEVICESCAN -a -m smart -s (S/../../6/06:001|L/../../2/03:008)
this schedules a short test every saturday starting at 0600, waiting an hour between drives, and long tests every tuesday, starting at 0300 and waiting 8 hours between drives.