I would say no, not necessary. I only used the rake on long, double coats. Collies, Chows and the like. I deshed with a curved slicker. You scoop the coat backwards on a dry dog. I also use it in the tub, soaped up, brush through, gets them clean to the skin and removes a ton of hair. Then while I'm rinsing, I'm brushing, even more hair.
Matts are from dead coat that is not brushed out. They are solid clumps and on Shepherds, come out pretty easily. Shedding is more individual hairs that are loose and clog the vacuum brush....
No beast so fierce
EPI, man aggressive, ball crazy, fearless protector, my heart