The Weakest Link: How Constraints Can Slow You Down

Have you ever been stuck in traffic and wondered what would happen if the road had more lanes?

Would there be less congestion, or would something else farther down get clogged instead?

Points where a system gets backed up like this are called Constraints.

They are the bottlenecks or weak links that keep a system from running faster and our lives are full of them.

Theory of Constraints

Typically this Mental Model is applied to manufacturing where it is called the Theory of Constraints. This theory was first proposed by Eliyahu Goldratt in his book The Goal. The premise is that any manufacturing process is a system where there is always a single point that prevents the system from producing more.

His idea states that the best way to get such a process running better and faster is to focus on these Constraints, either by improving that part of the system so there is more capacity or by at least making sure it is never sitting idle.

He also suggests that every system will always have a Constraint, that once you remove one another will appear, resulting in a never-ending pursuit of efficiency.

Not Just for Business

Constraints also appear in a whole host of systems outside manufacturing.

Traffic congestion is always a good example as we saw earlier. Invariably once one highway is widened another part of our commute gets clogged.

Network traffic on the Internet follows a similar pattern. Popular sites are perpetually adding more links coming in to their datacenters while Internet Service Providers are doing the same in an effort to remove bottlenecks for their subscribers.

Constrained at Home

Systems with Constraints can be found just about anywhere in daily life as well.

Think of laundry as a system … what slows you down?

Does the washer not hold enough clothes?
Does the dryer take forever to dry?
Do you have a small laundry basket and therefore need to make multiple trips up and down the stairs?
What could you do to make the laundry process faster?
Once that was optimized, what would hold you up after that?

Optimizing a System for … Input?

Typically we try to optimize a system in order to increase its output. We want to produce more widgets or get more laundry done in the same amount of time.

However there are some systems where you are better off optimizing for input. A prime example is personal finance, where optimizing for output is the fastest way to end up broke.

In thinking of personal finance as a system, what is the Constraint? In most cases it is your income. You can only ‘collect’ as much money in the system as you can bring in.

Of course you can work on saving as much as possible so as little money leaves the system as possible, but in the long run the single biggest bottleneck is going to be income. You can only pinch pennies so much but you can (theoretically) increase your income to infinity.