That is exactly the reason Micromat created the eDrive (a dynamically installable and removable bootable partition) and ProToGo (a minimal repair drive to go on a thumb drive) and Prosoft Engineering created Bootwell (their version of a bootable repair volume on a thumb drive). While Apple's Disk Utility has never been as robust a volume test and repair utility as TechTool Pro or Drive Genius, it has gotten better over the years, and having it on the Repair Drive that is part and parcel of the more recent versions of MacOS makes it my first choice for volume testing and repair.
