I have been fighting this battle for years and will say just this one more thing.

Contiguous data on a hard drive can become corrupt as well as non contiguous data. If it happens, it happens and it is a problem caused by the file allocation table messing up the "map". I have always found defrag and "you must have a virus" to be what techs try to sell people when they can't figure out what is wrong with a computer.

The advent of NTFS has made defrag almost of no value.

But as I say, this is a Ford vs Chevy discussion and I am out of it.