HS #130 2026.5.14
The 80/20 Principle and the 70% Rule
Have you heard of the 80/20 Principle? It’s a management concept that says 20% of the people in any group do 80% of the work (and hence 80% of the people do only 20% of the work). It’s also a quantification of the Law of Diminishing Returns. For example, I can spend 30 minutes a day lifting weights and in cardiovascular exercise, or I can increase my workout time four-fold and get even more benefit. However, it’s likely that I get 80% of the health benefit from just that first half hour. Putting in all the extra effort does not give that much more added effect.
Same goes with, say, buying a bicycle. I can buy a new quality bicycle for $600, or I get one that is three pounds lighter and perhaps more gears for $3000. But, the point is, I get 80% of the benefit of a bicycle for 20% of the cost.
I first learned of this when I was in college from the campus director of Campus Crusade for Christ (CCC). He challenged us in the leadership of the organization to apply the 80/20 principle to our time in college. In particular, he suggested that instead of putting in all of the effort needed to get A’s in our classes, we put in much less time (20%) and be satisfied with earning B grades. Then we could use the extra time in ministry and evangelizing with CCC, hence making a greater impact on campus.
I was a serious student, but also was a committed member of CCC who already spent 15 hours a week leading Bible studies, teaching the entire group, and actively sharing the “4 Spiritual Laws” with friend and stranger alike. So I took his recommendation seriously.
However, I came to a different conclusion. I decided that the 80/20 principle might well be applied to many areas of one’s life in order to maximize one’s total impact. However, each person may have a particular area of life in which s/he wants to really excel and strive for perfection. I realized that since I was bound for graduate school in mathematics, that my academic pursuits were the one area where I should nix the 80/20 principle and instead fully commit myself to excellence. However, I could and should apply the 80/20 principle to other endeavors, including my time in CCC. So, I cut back a bit on my ministry activities and learned more from my math classes (and graduated summa cum laude and PBK).
More recently, I have discovered another related principle which I call the “70% Rule.” I notice it when I watch professional tennis and when I play pickleball.
The idea is this: Competitors often hedge their bets. I notice that tennis pros engaged in a long rally may have an opportunity to make a decisive shot that will give them the point, but, fearing an error, they cautiously hit the ball at 70% (my estimate). As a result, often their opponent not only gets to the ball, but gains the offensive, and eventually secures the point.
I get angry with myself when I notice that I do the same when playing pickleball. I don’t trust myself with a put-away shot, so I compromise and hit one that I think will do the job. However, then I watch as my opponent, faster than I expected, gets to the ball and pushes one past me.
Both of these rules require wisdom and discernment to determine when they should and shouldn’t be applied.
Any good financial advisor will tell you not to put all your eggs in one basket. Diversifying one’s assets (essentially my 70% Rule) won’t lead to the greatest potential wealth, but it is safer – and that counts for a lot.
I just now heard an NPR story that Elon Musk will be investing $20 billion from Tesla into AI/robotic technology. Stock went down on the news. Musk doesn’t care – he does not live by the 70% Rule. He’s a success story.
However, I recently had a phone conversation with a college friend who, following his father’s dream, has committed his whole life (including mortgaging his house) into a design and production venture based on their 100% commitment to following God’s will. At age 69, he is realizing that it has not worked as planned.
Not safe; was it wise? Hard to say, but it is such people who change the world.
