So, until the next major iteration of DW is able to cope with APFS drives, this is better than nothing. I guess.
Don't confuse the various functions performed by DW (DiskWarrior), TTP (TechTool Pro), DG (Drive Genius), and DU (Disk Utility).
DU, TTP, and DG already cope with APFS drives as well as they are ever likely to. (I don't know for sure about DW but I strongly suspect it is the same.) They all can do Volume
REPAIR which, as indicated by the Disk Warrior tech involves creating a new volume directory. The volume directory is a
LOGICAL structure that is written on top of the physical structure. What these utilities cannot do is
OPTIMIZE the physical layout of the volume or files in APFS by placing files in contiguous sectors to speed access on HDs. Any location on a Solid State Drive can be accessed directly so any such
optimization would be pointless and in fact
could potentially to shorten the life of the drive itself. Since APFS is optimized for use on SSDs those optimization functions do not make sense and
are not available[//u] in the various disk utilities and never will be on APFS formatted volumes whether on an HD or SSD.
Repairing/Rebulding the volume directory will not and cannot repair errors in FILE structure or data contained in files and while any write operation could trigger the drive recognize a bad sector and remap it to a spare (if a spare sector is available), it cannot directly identify or even infer that media on the drive surface is flaking off much less repair or stop further deterioration. In fact you can perform Volume Repair on a drive that is technically in a failed status. Media flaking off of the surface of a drive is the most common type of HD failure and tdentifying that failure is the reason for performing a Surface Scan to identify if there are bad data sectors which is a good indicator of impending drive failure.
[u]NOTE: There are standard S.M.A.R.T. parameters for HDs such as reallocated sector count and Reallocation event count which do the same thing, but to the best of my knwkedge, TTP is the only utility that reports S.M.A.R.T. in that detail. For SSDs the equivalent would be Available spares and Percentage Remaining (again AFIK only available through TTP).
