Sorry I didn't give you enough detail. If you use Disk Utility you can only repair permissions. However, if you use a startup disk you can also choose the option to 'Repair' the OSX HDD or partition using Disk Utility from the startup disk (in utilities folder.)

There are some problems Disk Utility simply can't repair which is where 3rd party utilities come in handy & sometimes a necessity. Disk Warrior 's main focus is to repair the directory damage or corruption. And if you move large amounts of GB frequently this may not be a rare thing. Other utilities such as Norton & TechTool, etc. are more general repairers. Although Norton can often but not always also repair directory damage which can potentionally lead to the loss of many files if not fixed asap. eg: I just repaired my external HDD 2 days ago using Norton. It had become a read only hdd lol Nothing could be copied to or from it but!
I applied Norton from another mac & it fixed it just dandy. lol