Okay what the Hell. This shader compile behavior seems to be inconsistent, too, since I just started a new project on the Third Person template and it seems to have used the precompiled DDC! I also created a test with RT enabled to see if that was the variable at play, and it did “prepare shaders” post-launch, but only about 110 of them rather than 8000, and still looks to have used the precompiled DDC.
Something strange is afoot.