If older files, which are less likely to get extended, are placed near the start of the volume (top in the display) then the next defrag will be due later and take less time because the static files form a block at the start.
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When files are selected (automatically) to fill gaps, the oldest should be preferred. Perhaps you do this already but I don't see much evidence of it. Perhaps the priorities should be selectable in the Settings menu?
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The most successful re-orderer was "dog" or Disc Organiser of 1987, which was sadly never updated for FAT32, never mind NTFS! It was very fast and effective, using innovative algorithms - much quicker than Norton SpeedDisk, which didn't bother re-ordering.
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