Should you build it fast or build it correctly?

A few times last year I found myself in discussions weighing the pros and cons of building something fast versus building it correctly. By “correctly” I’m referring to taking the normative engineering approach to a problem, regardless of the pragmatics of timelines. The longer, proper, often more painful way (due to resolving long-standing technical debt) versus the faster, potentially hackier way that results in a faster delivery.

I don’t love characterizing the two alternatives as “correct” vs “fast,” because the dichotomy makes it seem like “fast” is interchangeable with “wrong.” But it’s not, and the choice is not that simple. Also “correct” doesn’t need to mean “slow,” but it often does.

One of my favorite and most repeated quotes is, “in theory, theory and practice are the same; in practice, they’re different.” In theory all of the code software engineers write is elegant, extensible and architecturally sound, but in practice there are deadlines, staffing considerations and needs of the business to consider. The Pareto Principle (or 80/20 rule) speaks to the unavoidable tradeoff between perfection and good enough.

I find “correct versus fast” to be a common debate between Product Managers and Engineers. Product Managers push for fast because they are trying to validate ideas with users as soon as possible. And for good reason; until you have real signal from users that a product is useful there’s no reason to invest dramatically in its upfront engineering cost. Engineers push for correct because that’s what we’re taught - proper code is idiomatic and elegant, and the value of a system lies in its resilience. Even knowing the hacky solution exists in production lingers in our heads like a mental thorn.

The best case is a compromise. Ideally Product Managers understand the present and future leverage of strong engineering practices and Engineers understand that a well engineered product with no customers is a dead product.

While it will always be more art than science, here’s how I’ve come to think about it:

  • If you’re building a product, bias towards building it fast.
  • If you’re building a platform, bias towards building it correctly.

Products versus platforms

By “products” I’m referring to the development of user-facing features. The value of products is customer happiness/product-market fit, which is incredibly elusive and makes iteration speed critical. When building products first focus on discovering value and then invest in making them resilient.

By “platform” I’m referring to the software layers on which products are built.1 The value of a platform is organizational leverage - how does it empower current and future product development? How easy is it for new engineers to grok the mental model of how it works? Are the primitives simple and extensible? Invest in building strong foundations for platforms. A hacky platform quickly becomes an onboarding, upgrading, and maintenance nightmare.

Which invites the next question: when can you tell when you’re building a product or a platform? The distinction is not always obvious, but here’s one heuristic I find useful:

TEST: If the thing you’re launching performs poorly, will it get killed or will it live on? In other words, do you need to build this thing for future reasons regardless of the immediate performance of this version?

If it can get killed, it’s a product.

If it will live on, it’s a platform.

For example, my team at work is the engineering owner of internationalization. Many of our projects require both shipping a feature to new users while evolving the underlying architecture of an existing, long-in-production codebase in order to do so.

Let’s see how this heuristic applies in theory: We want to release an existing feature to n new markets, and we need to add additional language support across all products in order to do so.

TEST: If the feature release to the new markets fails, will the release get killed?

Yes. If the feature performs poorly in these new markets, maybe it’s inappropriate for the customers in those markets. If metrics indicate poor customer behavior, the launch will be killed.

The feature is a product.

TEST: If the feature fails, will the work to add additional language support get rolled back?

No. We need additional language support moving forward anyway, and regardless of the performance of this release we will build and experiment with other market-specific features in these new languages.

The additional language support is a platform.

There is a tension here. The product component needs to be done quickly and the platform component needs to be done correctly. How you proceed really depends on the urgency of the business context, but in general if you know where the platform is going, you can use good tech debt to ensure that the feature is launched fast without sacrificing its long term ability to be integrated into the platform.

Of course, in practice, the lines between product and platform are often blurry - many projects are both product and platform, or start as one and end as the other.

I remember using Facebook before the launch of News Feed, when searching and reading individual profiles was the primary method of engagement. And then News Feed launched in 2006 and evolved into the backbone of the Facebook product experience. I can only imagine that News Feed started as a product experiment and, after an explosion in user engagement, quickly grew into a platform upon which many other products were built for years afterwards.

This commonly unexpected transition makes the tension between product speed and platform diligence important to continually revisit. In a long-enough time horizon, your most successful products often become platforms, which forces you to periodically reconsider their architectural foundations and iterative pace.


[1]: “Platform” is a loaded term in tech. I’m using “platform” within this post to refer to the shared services/abstractions/codebases that support applications at a company. There’s an entirely different conversation around platforms in reference to corporate positioning - Shopify and the Power of Platforms being a worthwhile example to read - which is similar in spirit but an entirely different topic.


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