Lead Time is the total time, from when the work is requested (form a customer) until the work is finished (the product is ready, the tasks is done). It is the time it takes to go through a Value Stream.
Lead Time is the sum of:
- Wait Time (sitting in the queue, ping-ponged between teams, ..)
- Preprocessing Time (planing, design, ordering, ..)
- Processing Time (doing it, building it, implementing it, ..)
- Postprocessing Time (inspecting, testing, ..)
In software development, especially long and invisible Wait Time can result in unexpectedly long Lead Times.