I have a 19 month old bitch who has always been 100% healthy, which I too now consider a rarity in the breed based on experience. I'm sure we'll hit something someday, but she's never had a limp or a cough or a sensitive tummy and she gets right back up after making a fool of herself going after a ball. She has no allergies, has only vomited a few times on car trips, and her hip prelim was excellent. She's ASL, and popular lines to boot.
I have a 5 m/o who also has been healthy as a horse. I can change foods cold turkey on both these bitches without loose stool (amazing, IMO) and both have been in fights and recovered without complications. She's a mish-mosh of working, Czech/DDR.
Statistically in my case this convenient lack of problem is unfortunately rare. My other GSDs have joint issues, had pano, allergies, enlarged prostate, sensitive skin and stomach, HD, unexplained GI complications etc. Both are ASL, although the one with the most issues and issues back two generations is WGL x ASL, then ASL for two gen. His ASL half had OFA Excellent.