How and Why to Partition the Mac Pro Internal SSD (ditto for any Mac)
The internal 2013 Mac Pro PCIe SSD (flash storage) is a very high performance device, at present the clearly preferable solution for high performance needs such as housing Lightroom catalogs, or actively editing large Photoshop files, scratch files, etc.
In some cases it might be useful to partition it into two partitions, such as Boot (system and applications) and Master (storage for files that benefit from high performance).