Emphasizing flow through the reduction or elimination of batching of work items is desirable but this is not always efficient or practical.
So what are some of the factors which might force us to batch work items?
Whether it is equipment, materials or people’s time, constraints are a common reason for batching work.
Let’s say we wanted to build a fence for a customer. While it might be better for the home owner for us to complete the full work for one section of fence at a time so that if the work spans multiple days the homeowner would progressively be receiving value, we might be forced to dig all the post holes first because we only have the use of an auger on the first day.
Maybe we are writing a software application which needs to have both English and French messages and we have no one on our team who can do the translation. If we only have access to a translation service for a week, we might need to batch the translation of all the screen messages and until that is done we can’t ship the product.
Sometimes there might be a mandatory dependency that prevents completion of subsequent work activities till a preceding one is completed for the entire batch. When building a house, you would normally wait for the entire concrete foundation to be ready before we’d start building on top of it. When frosting a cake, it doesn’t matter if half of the cake is baked – we’d wait till it is fully baked.
Economies of scale or a minimum requirement on how many work items can be efficiently produced might be another reason to batch work.
If I want to bake cupcakes, although the cycle time to bake and frost one cupcake is likely to be less than that of completing a dozen identical ones, the costs of wasted energy and ingredients from doing them one at a time would start to add up. Unless I have a customer who is willing to pay me that much more to justify producing single cupcakes, I’m likely to make them in batches.
This applies even if I’m trying a recipe for the very first time. While the volume of ingredient wastage would be reduced by baking a single cupcake, the benefits of baking a batch are still greater.
Or maybe I need to print some color business cards for newly hired staff from a printing agency. While there would be a per card cost, the overhead costs of setup, proofing and shipping might justify waiting till there are a few new hires rather that printing each set individually.
While some of these factors might present opportunities for continuous improvement to our delivery process, others are unlikely to be reduced or eliminated. We may wish to avoid batch work, but we do need to be pragmatic and accept that context counts.