I can't speak for @wraith, but I'm still waiting for a Core book errata after 3 years.* I'm (technically) still waiting for the Technomancer special material that is so desperately needed, also after 3 years.
*Not that I want the Core errata so much, but because I'm waiting for the Rigger 5 errata that is needed terribly.
If that isn't a glacial release schedule, I want a little of what your havin'. 
I would call that more an issue of release quality (both in terms of "the content that people want" and "well planned, written, and edited, and any errata addressed quickly")
In terms of quantity, not counting missions, stories, non-SR-rules products, or tarot decks, we've recently had:
2018
-so far:
- two rules supplements: Street Lethal, and in limited quantities Kill Code
- one setting supplement: Shadows in Focus: Morocco
- one adventure:Toxic Alleys
- likely
- Better than bad, a city book for Morocco, possibly something else by the end of year?
2017:
- Three rule (ish) supplements: Forbidden Arcana, The Complete Trog, Dark Terrors
- One setting supplement: Book of the Lost
- one adventure Ripping Reality
2016:
- Two rules supplements: Cutting Aces, Howling Shadows,
- Five setting supplements: Shadows in Focus: Metropole, Court of Shadows, Seattle Boxed Set, Shadows in Focus: San Francisco, Market Panic
- Two adventures: False Flag, Serrated Edge
Definitely slowed down from 2016, but on the order of a couple of rules supplements, a couple of setting supplements, and an adventure or two (plus missions, novels, Anarchy, etc) doesn't seem all that glacial to me. I guess our expectations may differ on how frequently material should come out.