Somewhat interesting. I am not a big fan of rules of thumb. To me, it's akin to when to retire; when to pull SSI. All very personal. But the article does suggest to analyze spending plans in detail. That's good advice that stands the test of time.
Prior to retirement, we lived modestly, but comfortably, on less than 50% of my gross pay. In retirement, we're spending more than that. However, it is still well below 70% of working gross income.
Got my hair cut today. Almost $40 all in (beverage, tip, etc). My barbershop is located inside a pub and doesn't hire kids. Nothing against kids, but, like doctors and pilots, I like my barber to have lots of experience.
YMMV!