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In Defense of Slack

When optimization is not optimal in life and business

Slack (adjective)

Not held tightly in position; loose.

“A slack rope”

We humans have a tendency to over optimize. To choose the straightest and tightest path to a goal. To cut out anything that adds unwanted fluff or slack.

You see this tendency everywhere. From the friend managing 9 credit cards to optimize their card rewards to the couple working 80 hour weeks to optimize their household income to the company that has cut their research team to the bone to maximize their profits.

These optimization can be very enticing. You can indeed reach a goal faster with a tight focus. But like a rope pulled too tight in the wrong place, too much optimizing can also make you fragile and likely to snap.

As I write this I am sitting and drinking a coffee (my preferred plain cappuccino with no added sugar) in the Frankfurt airport in germany. I am on a business trip and I have a 6 hour layover before my connecting flight. You might say that I have chosen an itinerary that is highly inefficient and unoptimized. I could certainly get to my destination much faster if I had chosen a different set of flights with a much tighter layover. If I had pulled in the unnecessary slack. But over the years of my international travels I’ve discovered that this optimization is not optimal for me.

For those of you unfamiliar, Frankfurt is a horrible airport. My least favorite airport by far out of any I have visited (and I've visited quite a few over the years). The Frankfurt airport is a sprawling monstrosity of twisting hallways, multiple security checkpoints, and unhelpful gate desks. As an entry to europe, going through immigration and customs and walking to your gate can take multiple hours on a bad day. And when you make it through this mess and arrive at your gate, there is no guarantee your flight won’t be moved to a different gate at the other end of the airport at the last minute causing you to retrace your steps through security and do the entire exercise all over again.

In contrast to my fellow travelers who are running through the airport in a panic with barely any time to reach their next flight, I much prefer to approach the Frankfurt airport with a relaxed mindset, to sit and drink a coffee, write something on my computer, and make my way in general direction of my flight as needed. The inefficient and un-optimal is optimal in this case for me.

Where do I optimize instead? My luggage. I run a very tight ship when it comes to what I’m carrying. Everything I brought for this international trip fits in a single carryon bag and a backpack. If a flight is cancelled or a connection is too tight, I dont have to worry about a checked bag getting lost in a foreign country. If I have to stay the night in Frankfurt due to a cancelled flight, I have all my toiletries, clothes, and entertainment devices with me. The optimization here is relaxing. It removes stress from my mind rather than adding to it.

The choice of where to add slack and where to pull it in can make a big difference in life and business. Take the example of just-in-time manufacturing. Just-in-time manufacturing is a model where products are created on demand, not in advance. Companies use this approach to optimize costs. Toyota is one of the most well-known examples of companies using this method. When a client places an order, Toyota only receives raw materials in the factory when it is ready to start building the automobile. This minimizes their inventory holding costs. With just-in-time, a company brings in the slack of their supply chain until it is tight and straight with no inefficiency or buffer.

It is brilliantly efficient and many companies try to copy the Toyota approach with their own supply chains. They optimize, drive efficiency, pull in more and more slack, and are rewarded with higher profitability. It is win-win-win… until covid happened in 2020 and the tight global supply chain snapped. Stores couldn’t get toilet paper, car manufacturers couldn’t get electronic boards to finish their cars, grocery stores shelves were left bare. Products across the economy couldn’t be built or delivered at exactly the moment when customer demand jumped, because there was no slack in the system. Companies that had just a little bit of slack in their system, were just a little bit more inefficient with their inventory, end up winning orders on delivery time alone. They were the only companies with products on the shelf to sell. Trading some nearterm efficiency and profit for longterm resiliency and slack was the right call in this case.

On a more micro level, look at how some couples approach their household budget. Where is there slack and where is it tight? I listen to quite a few personal finance podcasts and there are many examples of stressed couples fighting over the cost of an appetizer, hobby, or other small expense, sometimes to the point of near divorce. When you dig deeper, their troubles can often be traced back to a lack of slack. A buildup of quick decisions in pursuit of an efficient life have left them with very high fixed costs (an expensive house, an expensive car, a debt that has grown too large) while leaving zero breathing room for everyday expenses. Even a 5 dollar purchase can send them careening off the financial cliff.

The curious thing about these situations is that couples often made the decisions they did to be efficient. It was more efficient to take out the expensive mortgage on the dream home than to waste money on rent, it was more efficient to put everything on the credit cards to max out the points instead of saving up cash, it was more efficient to buy the expensive timeshare instead of planning out individual vacations over the next 30 years, it was more efficient to buy the new car rather than manage maintenance on the old one. Efficiency, optimization, and quick decisions, made over and over again until the couple couldn’t even breathe anymore from the rope being pulled so tight.

As I’ve gotten older I’ve come to appreciate slack. How sometimes the optimal thing is to be un-optimal, the efficient thing is to be inefficient. There is value in leaving room for coffee and a stroll, to leave time for play and relaxation, and not running directly to the next destination in life. Especially now that I have young children.

Earlier this year my wife left her very lucrative manager position to stay home with our two young kids. Our combined salary dropped in half. From an income perspective we are less optimized, we are less efficient. We cannot save as much money for retirement, we cannot go on as many fancy vacations, we cannot give as many gifts as we did before. But what we’ve lost in economic efficiency, we’ve gained in lifestyle and resilience.

This business trip I am on that is sending me through the Frankfurt airport could have been very hard on my family. In an alternative timeline my wife might have been left alone to juggle sick kids, daycare, and demanding full time work in an office for a week with no reprieve. Even if she had survived the stress of this one trip, it is not clear how many such trips our marriage could have survived in the alternative world where we both worked full time at demanding jobs. Instead we chose to have slack, and it makes all the difference.

Since my wife is full time dedicated to the kids instead of work we were able to pack everyone up and drop her and the kids at the grandparents house for the week I am traveling, something we could never have done if she was full time in the office. She gets to have helping hands, the kids get to see their grandparents, and I get peace of mind to knowing that what could have been a stressful week for the whole family is instead a fun and pleasant one for them.

Are we making as much money as we could be? No. But thats okay. I will defend the choice to build in slack. Life is better and more stress free with a little buffer built-in. In our case, the inefficient and un-optimal is just the thing we needed to live life to the fullest.


As for my flight out of Frankfurt. They decided to do the document check in the hallway before the flight. Everyone who was already at the gate waiting had to get up from their seats and leave the boarding area so their passports could be reviewed. Since I was slowly wandering in the hallway I ended up at the front of the line and had my pick of seats in front of the boarding gate. A blog post done and a prime seat in front of the gate, I think this relaxed 6 hour layover has been a success.

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