I too was skeptical about using defraggler but have now mastered how to use it. It seems that windows does a lousy job when it creates restore points and many are badly fragmented. What I do now is manage my own restore points. That is done by deleting the ones that windows creates and adding my own. I make a manual restore point after running my AV and defraggler. I delete all the ones that in the list except for the last one that I created. Thus I end up with 0 files fragmented and at 0 percent defragmentation. I now trust defraggler to the utmost!!!!!!!!!!!!!!!! I do this about once a month. My scans now show no fragmented files whatsoever.
Windows doesn't deliberately go out of it's way to create restore points with fragmented files that's the consequence of storing large files in one go they naturally fill in the gaps.
There's very little benefit from defragging "C:\Voume System Information\" Windows hardly touches it unless you do a System Restore, however defragging system files and program files would help improve performance.