Defragmenter considers defragmented hard drive as fragmented

As we all know, there are many defragmenting software's out there, some of them are free while some are not. I have used several of them.

It seems to that each defragmenter has its own definition of what constitutes a fragmented drive. I cannot understand this.

If you use one defragmenter and let's say it takes half an hour to complete its job. Now, if you use another one than it seems to go through the whole procedure again treating the hard drive as if it was fragmented.

In short, the second defragmenter sees the drive that has just been Defragmented as Fragmented.

Can anyone explain me why is this happening? It confuses me a lot.

Generally each one is developed to be different from the others. Also if they were all the same, then we would only be having one to use it.

Basically each defragmenter has its own way that it places the files. Although each one will say that it makes the OS run faster, however I have found that when it comes to defragmentation the best choice is to stick with one that comes with the OS.

I am saying so because the OS is the one who will be using these files once they have been defragmented. The one that comes with the OS will place the files for best possible performance with that particular OS.

I have been using Diskeeper for a while now and its very efficient. With the Windows tool, files would show fragmented even after a defrag. Whichever the program you choose, I guess its best to stick to one.