by Leon Rosenshein

Technical Debt and Agility

How much technical debt can/should you accrue? How agile can you be? What’s the connection?

I’ve written about tech debt before. The important thing to remember about it is that the metaphor only holds if you understand that it’s about opportunity cost and future value of money. It’s not a license to write crappy code and expect that the software elves will magically fix it later. Used correctly it’s building what you need now instead of what you think you’ll need in 12 months. Even if the rework later will have an overall higher absolute cost.

You do that for two reasons. The first and most important is that you can add value sooner by building what you need now. Because it’s the integration of released value over time that matters, not the instantaneous value released. The second reason is that while you have a good idea of what you’ll need in 12 months, and you probably even have the broad strokes correct, you don’t know the details yet. And the real cost is in the details, so you’re going to need to re-do it later anyway, so why waste time doing it now?

The question, of course, is how to balance the integrated value over time with the instantaneous value. Is another day’s work (25%) that produces 50% more value worth it? Over a week it is for sure. On the other hand, 50% more work for 1% more value takes a long time to be worth it. Probably much longer than it will take to figure out that you really should have done something different anyway. Your case is somewhere in the middle. You just need to figure out where.

That’s where agility comes in. Because agility is intimately tied to tech debt. The less tech debt you have, the more agile you can be. When you start a project you have no tech debt, and (almost) infinite agility. You can go in any direction with roughly the same cost. You just need to figure out the direction that provides the most value, and away you go.

As time goes on though, tech debt builds. And that starts to change the calculation. You spend more and more time paying the vig. That reduces the amount to effort you have to spend on adding value. Knowing where to add value also becomes harder. Unless you’ve already spent time and effort making sure you can change direction, changing direction takes more and more work.

That pushes you to spend more time up front preparing for changes. Keeping your tech debt low. Unfortunately, preparing for changes makes you more agile in the future, but doesn’t add current value. Which reduces your integrated value over time. So you don’t want to do too much of that. Which leads you right back to increased tech debt which slows you down.

Which, in a strange way, leads you to look for more frequent feedback and “optimize” your agility. By frequently looking at your vision/OKRs and comparing them to your current state you can adjust how much tech debt you carry and balance that with the agility you need to achieve your vision/objectives.