I'm new to this game as well, I found I have about .012 to .015" TIR on the outside of my Cushman 6" 4 Jaw Chuck.
(This is a threaded spindle, 1 7/8 8 TPI) When I dial in a piece of stock, I can get it down to <.002" on the piece held in the jaws, the business end.
I assumed the chuck was junk, but, the piece I am turning is well supported and runs true. Well, true as I can get it.
The "art" for me was fairly intuitive, I was surprised how easy it is to dial in a 4 jaw.