Have you read the help? Using MyDefrag
From the help:System Disk Daily, Weekly, and Monthly
Data Disk Daily, Weekly, and Monthly
- These scripts are designed for the system disk (the C: disk). They place the MFT and the directories at 30% into the data on the disk, and create zones from the beginning of the disk with files used when booting, files used by the most used programs, regular files, and spacehogs (less important files that take up a lot of space). Between the zones it creates gaps for temporary files.
- Daily is designed to be fast, but will not perfectly defragment and optimize the disk.
- Weekly does a more thorough job than Daily, but takes more time to finish.
- Monthly gives the best defragmentation and optimization results, but takes a lot of time to complete and is not recommended for daily use.
These scripts are designed for data disks (any disk that does not contain Windows). They place the MFT and the directories at the beginning of the disk, followed by a gap for temporary files and then all the other files. Defragment Only
Defragment all the files and directories on the selected disk(s). The script will first defragment files for which it can find a large enough gap, and then slowly defragment files that are bigger than the largest gap by shuffling data.
Are you comparing with another defragmenter? Use this script. MyDefrag uses wrap-around fragmentation, a concept unique to MyDefrag. The DefragmentOnly script will turn this setting off and is the only script that is more or less compatible with other defragmenters. For more information see the * IgnoreWrapAroundFragmentation setting in the MyDefrag manual.
Please note that it is a BAD IDEA to only defragment a volume, you should also optimize (the gaps on) a volume. Defragmentation results in more smaller gaps on the volume, because a file with 2 fragments will leave 2 gaps behind (worst case) and will make a big gap smaller. Gaps promote fragmentation and it is best to have as few gaps as possible. The "Defragment Only" script can be useful in certain situations, but it's usually better to invest a bit more time and run one of the Optimize scripts.