Which system is easier to support and improve?

It is more convenient to support and improve a system that has:

• Clear and understandable architecture with separation of responsibilities (e.g., layered architecture, microservices).
• Well-documented code and business logic.
• Modular and integration tests that facilitate checking changes.
• Use of coding standards and design patterns.
• Automated build and deployment processes.

Such a system allows for quicker understanding of the code, reduces the risk of errors during modifications, and simplifies scaling.