The "rookie-pro" and "promotion chain" structures are examples of how even simple structures can provide important and counterintuitive insight that affects us in many different arenas.

The family of systems thinking archetypes could be extended to include system dynamics structures such as these.

Among the many instances where the "rookie-pro" structure arises are:

• Inventory level as sales rate increases ... as the sales rate increases the inventory level falls.
• Average age of trees in forest ... as the rate of cutting old growth increases, the average age of trees in the forest falls.

The "promotion chain" or, it might be called, "progression chain" structure applies in other areas as well.

• Software age mix ... it gives rise to the legacy software maintenance problem because the time to develop new software may be a year or two, but may need to be maintained for 10 or more years
  • The danger for the company: losing people because they don't like to be assigned to maintaining legacy software.
  • The danger for the employees: getting trapped in a position maintaining legacy software without the opportunity to upgrade skills.