I think I am just commenting on this thread to punish myself, as I've only had access to a 401K for one year of my working life, and I'm turning 31 this year. My average annual salary in my working career is close to the 401K annual limit, making maxing it out and also eating food impossible.
Anyway, I always sought to have a net worth equal to my annual salary at age 30 (the "standard" goal from above) and I did manage to achieve that, depending on how you interpret annual salary. I tend to focus on savings RATE more than anything, rather than hard numbers. Always been able to stay above a 15% savings rate, getting as high as 59% when I was making the big bucks at $47K per year.
The savings rate shows the real grit, as numbers are meaningless if you have $500K in your portfolio but spend $150K per year.