This use case is applicable to software development organizations where the business demand per software system fluctuates over time, and therefore, the number of developers necessary for each software system changes and as such, the workforce allocation should be adjusted.
Such circumstances are oftentimes the case where software systems are IT applications used by the business side of the same company, e.g., sales, finance, operations, etc.
Generally, the internal customers will already have IT applications that support their business processes. In this case, the IT organization just has to maintain the systems (keep the lights on).
However, sometimes the business side needs to seize new opportunities or experiences changes in their business processes, with the subsequent need to extend or adapt the underlying IT systems.
The developer resources then need to be shifted from the software systems that were formerly in business focus to the now business-critical software systems.