DeMarco defines slack as “the degree of freedom required to effect change. Slack is the natural enemy of efficiency and efficiency is the natural enemy of slack.” Elsewhere, he writes: “Slack represents operational capacity sacrificed in the interests of long-term health.”
Slack time prevents us from getting locked into our current state, unable to respond or adapt because we just don’t have the capacity. Having a little bit of wiggle room allows us to respond to changing circumstances, experiment, and do things that might not work.
To illustrate the concept, DeMarco asks the reader to imagine one of those puzzle games consisting of eight numbered tiles in a box, with one empty space so you can slide them around one at a time.
The objective is to shuffle the tiles into numerical order. That empty space is the equivalent of slack. If you remove it, the game is technically more efficient, but “something else is lost. Without the open space, there is no further possibility of moving tiles at all. The layout is optimal as it is, but if time proves otherwise, there is no way to change it.”
Most of the time, though, it’s critical to guard your slack with care. It’s best to assume you’ll always tend toward using it up—or other people will try to steal it from you. Set clear boundaries in your work and keep an eye on tasks that might inflate.
Only when we are 0 percent busy can we step back and look at the bigger picture of what we’re doing. Slack allows us to think ahead. To consider whether we’re on the right trajectory. To contemplate unseen problems. To mull over information. To decide if we’re making the right trade-offs. To do things that aren’t scalable or that might not have a chance to prove profitable for a while. To walk away from bad deals.
Being comfortable with sometimes being 0 percent busy means we think about whether we’re doing the right thing. This is in contrast to grabbing the first task we see so no one thinks we’re lazy. The expectation of “constant busyness means efficiency” creates pressure to always look occupied and keep a buffer of work on hand. If we see our buffer shrinking and we want to keep busy, the only possible solution is to work slower.
Trying to eliminate slack causes work to expand. There’s never any free time because we always fill it.
Amos Tversky said the secret to doing good research is to always be a little underemployed; you waste years by not being able to waste hours. Those wasted hours are necessary to figure out if you’re headed in the right direction.
Not Too much
- Too much slack is bad because resources get wasted and people get bored. But, on the whole, an absence of slack is a problem far more often than an excess of it. If you give yourself too much slack time when scheduling a project that goes smoother than expected, you probably won’t spend the spare time sitting like a lemon.
- Maybe you’ll recuperate from an earlier project that took more effort than anticipated. Maybe you’ll tinker with some on-hold projects. Maybe you’ll be able to review why this one went well and derive lessons for the future. And maybe slack time is just your reward for doing a good job already! You deserve breathing room.
Not too Little
- Once in a while, you might need to forgo slack to reap the benefits of constraints. Lacking slack in the short term or in a particular area can force you to be more inventive. If you find yourself struggling to come up with a creative solution, try consciously reducing your slack. For example, give yourself five-minutes to brainstorm ideas or ask yourself what you might do if your budget were slashed by 90%.
- Not having slack is taxing. Scarcity weighs on our minds and uses up energy that could go toward doing the task at hand better. It amplifies the impact of failures and unintended consequences.
Slack is vital because it prevents us from getting locked into our current state, unable to respond or adapt because we just don’t have the capacity.
The world is the way it is and learning to see that reality is critical. It changes our understanding of what is possible. If no one has ever done the work you hope to do then you might be deluding yourself. If, on the other hand, there’s a well-trodden path and people have gone on that path, then you might be able to follow it
- Have time open to handle the inevitable shocks and surprises of life.
- If every hour in our schedules is accounted for, we can’t slow down to recover from a minor cold, shift a bit of focus to learning a new skill for a while, or absorb a couple of hours of technical difficulties.
- Having a little bit of wiggle room allows us to respond to changing circumstances, experiment, and do things that might not work.
- Slack consists of excess resources. It might be time, money, people on a job, or even expectations.
- Typically, you need more slack than you expect. Unless you have a lot of practice, your estimations of how long things will take or how difficult they are will almost always be on the low end. Most of us treat best-case scenarios as if they are the most likely scenarios and will inevitably come to pass, but they rarely do.
- You also need to keep a vigilant eye on how fast you use up your slack so you can replenish it in time. For example, you might want to review your calendar once per week to check it still has blank space each day and you haven’t allowed meetings to fill up your slack time. Think of the forms of slack that are more important to you, then check up on them regularly. If you find you’re running out of slack, take action.
- Slack time
- Time management
- Time prioritization