Used it for ten years but have recently changed to Puran Boot-Time defragger freeware, with its Intelligent Optimizer enabled on the Additonal Operations tab.
Would be interested in hearing others' comparisons of the two. Puran seems to do a lot more, especially at boot-time when System Files are not in the way.
It will couple defrag+optimizer with chkdsk /f if selected for boot scan. Running it this way on my last ten installs found 3 cases of multiple disk errors I would likely not have found otherwise, so I like that too.