my practice use defraggler to defrag once a month:
1) file with more than 3 month old last modify file to keep out appended log file / virus signature database to defrag
2) excluding all temp files, browser cache files, files in recycled bin
3) always don't perform free space consolidation (may be call full defrag) except I need to clone image with Paragon Backup & Recovery 2014 Free Edition because already fragmented file to be restore in the same fragment situation.
4) occasionally defrag can keep up NTFS allocation performance & eliminate low performance small size files which can hurt performance