Waiting waste is one of the most prominent and important types of waste. Why? Because waiting reflects the scarcest resources of our lives: time. If we want to reduce spoilt time, we need to reduce waiting waste. Measuring it is a necessary ingredient to manage this.
There are four aspects of waiting you can measure:
- The overall waiting time from first occurrence until final closing of an issue (a to-do, a decision). In Lean this is called “lead time.”
- Time required to perform actual tasks. If you look at a single task, this will be all. For repetitive tasks (e.g. processing e-mail), you can measure the time between to tasks of the same type. This is called “cycle time.”
- Waiting for input or help from others.
- Not working on an issue but keeping it untouched. This can be caused by other things you have to do or just because you do not bother. This is called “idle time” (although you may do other things in the meantime).
If you look at these four aspects, the first one is simply caused by the other three.
To reduce lead time you need to improve performance, waiting for others, and idle time. There is a minimum for the first two, you cannot reduce them to zero. You can try to increase your performance, and you can communicate the urgency of your issue to others.
If you look closely, the main reason for self-inflicted waiting is idle time. In the long run, this leads to inventory waste. Your to-do list grows, and grows, until you are not able to handle it. It may be the other way round: if your to-do inventory is too big, it will cause idle time. In most cases, waiting and inventory waste will be a vicious circle. Setting your priorities straight, you should reduce idle time first.