The first application should make the second easier to build

Most delivery engagements are evaluated on a single question: did the software arrive, roughly on time, roughly as described. It is a fair question. It is also incomplete, because it treats each project as an isolated transaction rather than as an investment in how the organization builds.

A more useful test is what happens at the start of the next initiative. Does the team begin with reusable architecture, understood delivery patterns, established deployment practice, and internal experience from the first build — or does it begin exactly where the last one began?

This is not a promise that the next project will cost less. Scope varies, and a second initiative can easily be larger and harder than the first. The claim is narrower and more defensible: the next initiative should not have to start the learning curve from zero.

What compounds is specific. Patterns for integration with the systems of record. A deployment path that already exists. Security review that has already established what good looks like here. Internal engineers who know the working method rather than having read about it.

The commercial implication is uncomfortable for a lot of delivery models, because compounding capability inside the client reduces the structural need for the vendor. That is the intended outcome. Dependency should be earned through value, not engineered into the relationship.