It is typically more difficult to eliminate the variability of demand and cycle times, so this variability is managed. The combination of lean practices used to manage the variability is known as Pull Systems.
The overall level of demand, such as incoming orders, can vary significantly over short periods of time. Additionally the product mix of demand creates further variability. Finally, the cycle times to do the work in each process step are not the same. Eliminating this variability is either difficult or costly to do.
To manage this variability, Pull Systems are established. Pull Systems are various lean practices & tools used to level load the demand and regulate the work between process steps to create single piece flow.
The Lean CFO must work with the Lean Team to ensure that demand & cycle times are measured accurately & consistently throughout the organization. Demand is measured as Takt time, which is simply the level of demand as measured in time, not units. Lean companies measure demand in Takt time so it can be compared to the total cycle time, which is the total time it takes to produce one product.
Flow is achieved, and proven to work, when the total cycle time = 80% of average Takt time. Having poor measurements of demand & cycle times will impact the effectiveness of continuous improvement activities.