Unless i'm reading your post wrong Nihil, There's no need to Defrag a SSD as majority SSD makers inlude optimized technique that utilizes the "TRIM" command.
Sorry! I was referring to these new electro-mechanical traditional HDDs. Whilst an SDD does not require defragmentation (it is a waste of time and counter-productive), the old style drives with read/write heads still do.

Microsoft have erred on the side of caution, and the last time I read about this, they would defragment about 1 out of 5,000 SDDs sampled, but miss about 15% of regular HDDs. With these newer HDDs, that percentage will be a lot higher. In the case of the drive I mention in this thread, that would be 100%.

So, what I am suggesting is that if you have a recent EM HDD you may well need to manually defrag it, as it may be misidentified as an SSD?