I have 2 double coated dogs (1 is GSD), and I have had varied experiences with their shedding.
Overall, my GSD has more "everyday" shedding, but neither of them have a super heavy coat blow. My keeshond used to have a couple weeks of dramatic (but controllable) coat blow spring and fall, but not anymore. I think quality of diet plays a big part in overall shedding and even how they blow their coat (my info is anecdotal at best, though); and I've heard this from other GSD people as well.
Regular grooming absolutely helps - I definitely notice the hair accumulate when I get a little lax on keeping up with brushing. What tools are you using? A good undercoat rake is a lifesaver! Nigel is right, air force dryers are the bomb. I'm lucky enough to have a local pet store that has a self serve dog wash, including a force air dryer! We use that every now and then when the weather is not-so-nice. And my sister (who has Siberian huskies) has a force air dryer that we borrow every now and again when we can use it outside.
If your boy is really, really sheddy, maybe it's worth bringing him to a professional groomer a few times a year for a "de-shed" treatment?
Dover von Ziegeln Zage (GSD, 3 yrs)
Dutchess Lena of Black Lake RATI (Keeshond, 12 yrs)
“Once you have had a wonderful dog, a life without one, is a life diminished.”