Author: Jurgen Appelo

MIED stands for "Member of the Institution of Engineering Designers" and for "Maritime Improvised Explosive Device". It is also the acronym for Maintenance, Improvement, Extension, and Disruption, the four kinds of work we do when investing time in our products and services.

For example,

• Sometimes, you recharge your phone. (= Maintenance)

• Sometimes, you update the existing apps on your phone. (= Improvement)

• Sometimes, you install new apps and add new capabilities. (= Extension)

• And someday, you will replace the entire phone with something better. (= Disruption)

It is usually impractical or impossible to do all these things simultaneously. We allocate different time slots to them. (When trying to upgrade my phone to Android 13 yesterday, the device insisted that I first recharge it to a sufficient power level. The improvement step required a maintenance step!)

You will find the same four categories with nearly all your work on the products and services you offer to your customers.

• Sometimes, your team does maintenance work on a value stream.

• Sometimes, your team spends time implementing minor improvements.

• Sometimes, your team works on significant extensions to current capabilities.

• And someday, your team disrupts an existing value stream by working on a complete replacement.

Let's call them the four investment horizons.

Note: The name "investment horizons" is based on the Three Horizons Model developed by McKinsey, with Maintenance added as Horizon 0.

Traditional organizations often see these kinds of work happening on different time scales. But in many environments, that doesn't work anymore. Entrepreneurial professor Steve Blank said that all horizons could happen simultaneously nowadays. So, let's make sure we organize ourselves like that!

In the unFIX model, you can use the four markers M, I, E, and D to indicate where the work happens. Who is responsible for Maintenance? Are Improvement and Extension ideas gathered on a shared backlog, or are they kept separate? And how does the organization reserve time for true Disruption?

It may be unwise for one team to do everything. But, somehow, your organization certainly should do it all. Better plan for it!