Agile development has evolved from lean product development for a special case.
What is agile? Many people think it is a software development principle. They don’t realize that agile is a subset of lean product development, and instead see the grouping of work into small batches as a software industry breakthrough. As software has become an element of many new products — e.g., autos, printers, appliances, industrial equipment — organizations have found significant benefit in adoption of agile processes for the software side of the product. As they attempt to migrate agile to hardware components, complex products, or the development system as a whole, problems arise due to key aspects of lean product development being stripped out or oversimplified. The more agile is scaled, as in SAFe (Scaled Agile Framework) or other scaled methods to enable more complex development, the more agile reverts to lean product development methods.
Software and hardware have different rhythms of development: short cycles for software and longer cycles for hardware. Hardware development usually comes with integration of various mechanical parts from different suppliers that need to be combined and work together. There are critical learning aspects that must be accomplished through proactive learning cycles. The integrated product often needs to be tested for performance and endurance, which all by itself requires time. Software, in contrast, can be tested quickly and doesn’t require endurance tests. Development of both aspects must be synchronized to form the final offer for delivery of the customer experience. This necessitates principles of lean product development — e.g., set-based design, learning cycles — that allow for the varying cycles of product development to be integrated within the framework of an overall project cadence. Neither conventional product development methods nor agile methods alone are able to accommodate this complex development work.