Here's an idea for PSA to help with grading times..
To be fair to the new card collectors, so that the hot rookies can get graded within the season they are playing, maybe those items should be sent in separate much like the pre and post 1956 cards specials that used to exist. So for 2019, you must send in those cards by themselves in lots of 25 or 50 or more. I doubt the big hold up is a lot people sending in loads of 1940's, 1950's and 60's singles. This should help with training, since the new cards probably won't be hard to identify nor authenticate, just grade and go.
Segmenting the order into specific lots should help the graders. Maybe even do it by decade. Or by auto, no auto, etc.
FYI, I don't buy new cards (hot rookies) due to their volatility.