These excerpts from the “Earl Scruggs & The 5-String Banjo” book opened up the “Banjo Doors” for me.
Direct from Mr. Scruggs himself…

The Reverse Roll
Waltz rhythm
The Vamp
Boogie Woogie
Backup Run

Earl lays down the law.
If you listen to him closely you begin to understand what J.D Crowe and John Hartford were talking about:

J.D. Crowe talks a lot about the “Three T’s”
That would be timing, tone and taste.
He doesn’t merely talk about them, he embodies them.
Without timing you have nothing.
Next, as with any musical instrument, the tone should be pleasant to the ear.
And last but by no means least, taste.
In my own humble opinion taste is the sum of timing and tone, which leads me to John Hartford’s philosophy about style.
He states, “Style is created by limitations”.
Simply put, if you can’t or won’t play something then it’s not your style.

The moral of the story is:
Six+ decades later Earl is still the man.