When is Scrum Appropriate

According to the 2020 Scrum Guide where Scrum is defined, “Scrum is a lightweight framework that helps people, teams and organizations generate value through adaptive solutions for complex problems”. Scrum is most suitable for product development that lack clear definition or comprehension with the definition of product and the work involved in making the product. We call this type of work complex product development. In these cases, new information can emerge at any time. Scrum enables the flexibility to change direction without wasting effort. While it's possible to use Scrum for routine repetitive, and predictable work, its benefits and costs in such cases may be questionable. We call this type of work simple product development. For simple product development, upfront detailed planning is possible and following the plan will be adequate to reach the goal.

In order to asses the complexity, one needs to look how much of the product is know/unknown and how much of the skills to create the work is known/unknown. We also need to look at the environment the product belongs to that can change the need or the product itself. The unknowns in all these areas will affect how much of the work can be predicted upfront. If the work you are undertaking in unpredictable, crating a detailed plan upfront and sticking to it will be both waste of time and possibly end up creating a product that is unsuitable for the changed environment. In a complex product development, the issue at hand has never been previously resolved, and a solution has never been devised, which means there's no established formula to rely on. In these cases, an empirical process control will be better suited. Scrum provides a simple and adaptable framework based on empiricism. It’s iterative incremental way of working help to produce small incremental value, inspect it and adapt as needed.

Scrum or an adaptive process is NOT necessary if simple or complicated product development. In Simple product development, most of the elements are known and an upfront plan can be made. In a complicated product development, about 70% about the product and the work very well defined.  In the case of Complicated product development, with some amount of work upfront, a good plan be created and then be followed to build the product.
Example of simple product development: The table I am using right now was bough on Amazon. It was 5K positive reviews which might means that about 5K people built it successfully by following the instructions just as it is on leaflet that came with it in the box. I don’t really need an iterative incremental process for building that table. And example of a complex product development: The work of building a mobile App such as Uber in 2007-2010 was a complex product development for many reasons including 1) the customers were new to this way of service. 2) The technology was new.

There are a few models available to asses the complexity. Two of them are Dr. Ralph Stacey’s work (Stacy Matrix) on complexity and Dave Snowden’s work know as Cynefin framework.

Scrum operates as an adaptive process primarily suited for handling complex product development. However, its effectiveness hinges on the organization's willingness to embrace changes in plans. Several factors may influence this stance. For instance, some organizations may resist change because they perceive no immediate need for it. An organization's core objective is to efficiently complete its tasks, and if it firmly believes that traditional processes are vital for its operations, Scrum may not offer discernible benefits to anyone involved.
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Scrum practices are rooted in the principles of empirical process control, relying on adaptation for both product and process improvements. The crucial elements of inspection and transparency are essential for facilitating adaptation. If an organization lacks transparency due to various reasons or if the organizational culture and environment do not foster a safe space for transparency, the empirical process control, and consequently, the framework will not be useful.


Further Reading:
Cynefin framework by  David Snowden
Dr. Ralph Stacey’s work (Stacy Matrix) -  Ralph Stacey's Agreement & Certainty Matrix