There's a very precise answer to your question: It depends.
There's no question that as time went on, the record companies cut more and more corners. The mid-70s saw the rise of audiophile labels like Mobile Fidelity, as well as direct-to-disk recordings. So that's a good indication that mass-market quality had fallen pretty far by that point. Things certainly didn't get any better in the 80s, as companies started diverting resources to digital (and cassette).
Except maybe for some boutique outfits, I don't think any labels were immune to this. I collect jazz records, and I certainly see the phenomenon even on a label like Blue Note.
If you can't explain how it works, you can't say it doesn't.—The High-End Creed