Is six sigma still considered a best practice ? If so why doesn’t six sigma get more attention in the software community ?

“Consider this hypothetical. You make spare parts and promise 10-day delivery. Over the course of three deliveries, your customers receive their parts on day 5, day 10, and day 15. On average 10 day delivery. Over the course of the next three deliveries they received their parts on day 2, day 7, and day 12. An average of seven days, a seemingly big improvement in the customer’s experience. But not really—you might have some internal process or cost improvements, but the customer has experienced nothing but inconsistency! With Six Sigma, your customers would receive all three of their deliveries on day 10, or in the worst case, on day 9, day 10, and day 11. Six Sigma in other words is not about averages. It’s about variation and removing it from your customer’s interface with you. — Jack Welch, from his book “Winning”