.. the default scan time was 10 mins (600 secs). This meant my WHS was scanning the music directory all the time. I’ve gone and reset this up to 16 hours (60000 secs) to let my HDD spin down overnight etc.
I’m a novice too, so I hope an expert will reply.
But as I read the config file (http://wiki.fireflymediaserver.org/Config_File), the always_scan setting should prevent Firefly scans from keeping your disk awake all night. If set to 1, then the scanning happens continuously, and the problem you point out happens. But the default value is 0, which is supposed to mean that when no users are connected, Firefly will stop scanning.
So, if your default scan time is 600 secs, and your always_scan setting is 0, and if scans still happen even when no users are connected, then you have discovered a behaviour that contradicts the config file documentation.
Independent of the always_scan setting, though, I think you have a point. I rarely add music to my collection, and I can pus the start scan button when it happens. So I’ve followed your advice and set my rescan interval to 60,000 seconds.