That's great if you only machine cylindrical stuff. I have several 3 jaw chucks and have not used them for years. If you
use a 4 jaw all the time, you get very adept at centering a part. Not only that, it is easier to center a part with the 4 jaw
than swapping out two heavy chucks. But then I machine on all kinds of shapes and I'm a 4 jaw kind of guy.
I was just referring to the OP stating he was writing coordinates down so it was repeatable. So not having to indicate all the parts. With a 4j you will be indicating every part either way.