- Clayton Christensen 

It's happened at work. When something needs to be shipped on an incredibly tight deadline, we decide to implement the feature to be shipped in a hacky way. Just this once. 

It's happened at school. When multiple courses are on offer, we decide to take up the one that will get us through with less effort even though that may not be interesting. Just this once.

It's happened at home. We snooze the alarm because we need a little more sleep which is more important than going out running. Just this once.

Only it is never just this once. 

We make the decisions that we'd expect ourselves to and we make decisions that we won't regret later a majority of the time. Which is all in situations that lie in the in between and not in the extremes. Because there is no trade off. We don't consciously think of the options available and then pick one. The decisions are made subconsciously. 

The minority cases where we don't necessarily make the decisions we'd expect ourselves to (rationally) and ones that we regret later on are all in situations that lie at the extremes. These are cases where we clearly see the options available to us and then pick one deliberately. 

When we read about how following a routine for 21 days turns it into a habit, what is actually happening is that the decision making for the routine in question is being moved from the extremes to the in between. Once that happens, there is no longer an active choice involved in following that routine. It now happens subconsciously. 

Culture at home, culture at work, culture with friends, are all developed in this manner. How often do you do things against the ideal culture that you have in mind that you tell yourself are 'just this once'? Answering this will tell you how far away you are in practice from your ideal culture. 

Writing things down helps. 

I have written often about how maintaining a weekly planner helps me get more things done than otherwise. Companies do the same now by pasting their values across the office space, on the walls, in the corridors. When things are written down, they are brought back to the surface of the conscious mind every time we see them. This makes decisions that go against them conscious. 

Even if it has become a habit for your team to hack your way to shipping as per deadlines, and it is a subconscious choice to take that route when such situations arise, having to look at quotes and statements that coerce you to not make such decisions everyday at the work place forces these decisions to not be made subconsciously. These are trying to push what is in the in between but not in alignment with what is expected back to the extremes for re-evaluation. Looking at my plan for the week when I wake up in the morning has a similar effect on me. 

Our habits and our cultures are built at the extremes. So, if you have to make trade offs or cut corners under extenuating circumstances (as Clay Christensen puts it), beware of doing something 'just this once'. That will likely be the foundation for doing it more often.