Iteration vs Sprint, and cadence. While these terms have a lot in common, each of them has a slightly different flavor to it. They all have to do with Agile project management frameworks and contribute to the predictable delivery of digital products and services. But how do they differ?
What is an iteration in Agile?
In life, there are many different units to convey small and large numbers which are typical of certain phenomena. For instance, we use miles to talk about distance. To drive one mile means to drive for 5,280 feet. During each mile, your car does a lot of work to produce the energy necessary for taking you to the place you want. And once you pass one mile, another one begins with the same number of feet (and your car engine is still working). With each mile, you get closer to the end of your journey.
You can observe a similar process in Agile. In Agile, you divide projects into repeatable periods of a certain length or duration that you call iterations. They usually consist of the same procedures, sequences, and processes. During each iteration, teams work on a certain piece of work that holds some value to your stakeholders. As such, an iteration in Agile means a time unit for one repeatable period (loop) whose goal is to generate some valuable outcome. And when the iteration sequence approaches some endpoint or end value, it becomes the starting point of the next iteration.
The duration of one iteration varies, but it usually does not take longer than one month. Whether an iteration lasts a week, two, three, or four depends on the project and organization, but typically it is two weeks. The iteration length is usually fixed throughout the entire project. But contrary to a mile, you can change the iteration length if there is such a need. Or your team would like to try working in longer or shorter iterations to find the most optimal one.
As per the Agile approach, a project is exclusively made of a sequence of iterations (with an exception of planning and vision phases that occur before the development begins). Generally, iterations follow calendar weeks starting on Mondays and ending on Fridays. But this is not a strict rule and teams can adopt a different time convention (just as they can adopt different iteration lengths).
In modern Agile development, the term “iteration” is essentially synonymous with the “time-box” and “Sprint.”
Sprint meaning in Agile
To sprint means to run over a short distance at the maximum speed in a limited period. It is used as a way of quickly reaching a target or a set goal. Sprints in Agile work in a similar way. The main difference is that “runners” do not compete with each other, but cooperate. Also, the Sprint is considered finished on the planned date, not when sprinters cross the finish line.
A Sprint in Scrum means a single time-boxed iteration of a continuous development cycle that belongs to a Scrum methodology. During a Sprint, a team needs to complete all the planned work within a designated short time frame and prepare it for review. The Sprint duration in Scrum is usually two weeks but could be up to a month. During that time, the team works (“runs”) at their full speed to reach the goal by the end of the Sprint.
Each sprint begins with a meeting, called Planning. During this meeting, the Product Owner (PO) and Developers agree upon the scope of work they will complete during the Sprint. During the Sprint, the team holds daily stand-up meetings to discuss progress and brainstorm solutions to challenges. At the end of the Sprint, Developers present their completed work to the PO to either accept or reject it.
Sprint is the heart that beats the cadence for Scrum (more on cadence later).
One Sprint loop. All Sprints are iterations but not all iterations are Sprints. So how do they differ?
What is the difference between iteration in Agile and Sprint in Scrum?
The standard duration for an iteration and Sprint is two weeks. So if you look at it from the time-box perspective, they are essentially the same things. In other words, Sprints are the domain of Scrum, whereas iterations are a more general Agile term. But there is one important difference that stems from the Agile methodology and Scrum framework.
While Agile is a set of principles, Scrum is more about getting things done. Such an approach is reflected in Scrum Sprints. On the one hand, Scrum team members sprint together to deliver acceptable work on time. But on the other, they cooperate to solve challenges and look for ways to improve their workflow to increase efficiency.
Cadence meaning in Agile: Scrum, SAFe®, Kanban
Let’s begin with a simple analogy to explain a cadence first.
The human heart beats according to a regular pattern that consists of alternating contraction and relaxation. Again and again. The heartbeats make the rhythm—or a cadence. So cadence is the rhythm of executions, a flow of events, or a pulse if you will. But that pulse is different in humans. A normal heart beats around 50 to 99 times a minute, which means there is no single fixed cadence for cardiac cycles in all humans.
Just like the pulse of our hearts, the pulse of Agile can vary too. So let’s take a look at two different cases of forming cadence in Agile methodologies.
Cadence in iteration-based Agile (Scrum, SAFe, XP)
In iteration-based Agile like Scrum, SAFe®, or XP (Extreme Programming), iterations have fixed, time-boxed durations that usually take less than a month. When you carry on with your iterations one after another and keep their duration consistent, you form a cadence. Like a beat of a heart—one after another.
In the example above, you know that each subsequent iteration will last three weeks. Therefore, you can estimate and schedule your work in advance and deliver software with a regular rhythm. Please note how user stories fit into one Scrum iteration (Sprint), meaning they are to be completed at the end of a Sprint.
Cadence in flow-based Agile
When it comes to flow-based Agile like Kanban, there are no iterations, no time-boxing, only a continuous flow of work. Therefore, Kanban cadence is a continuous flow. Still, you are free to decide when you will hold planning, a release, and a retrospective. They all can happen regularly but independently at differing rates. For example, you could schedule releases to take place every Monday, planning every two weeks, and retro a week later after planning.
Here, the unit of work is a Minimal Marketable Feature (MMF). Like User Stories, it should also be as small as possible, but unlike them, it does not need to fit into a single time-boxed schedule. Instead, an MMF can flow along with a number of processes until it delivers some releasable value.
Cadence vs Iteration
Iteration is a unit of time like a second, an hour, a week, or a month. It is a point of reference for a single time box. Cadence, on the other hand, is a rhythm that consists of a series of iterations that take place one after another. If an iteration takes two weeks, then it is an iteration of a two-week cadence because the “heartbeat” happens every two weeks.