I have successfully passed a STA indoc, and will tell you right now, I would have failed on the ruck run if I hadn't been doing it off and on, on my own.
Caleb, that illustrates the main point I'm trying to make. You didn't do STA indoc right out of high school. You did basic and infantry school at a minimum, and probably served in a battalion for a while before you tried out for STA, right? By that point you knew what would be expected of you and how to train for it. That is far different than some kid at home reading a SEAL website and thinking he needs to start ruck running now. Would you not concur that it would have been a waste of your time to ruck run prior to enlisting, or at least much less productive than crossfit/lifting/running/cycling/swimming?