Good design adds value faster than it adds cost.
Thomas C. Gale
A good software architecture is not only technically satisfying, it is also economically sound.
A reasonable investment in software architecture pays. But how much should be invested? That depends primarily on project size, project complexity, quality requirements and organizational set-up.
The following diagram is a guideline for optimal architecture investment.
Too little architectural work will result in immense amount of rework, even to the extend of project cancellation. Excessive architecture work do decrease the amount of rework needed, but for most projects this might not be efficient.
The right amount of architecture work is essential for optimal Return On Investment.
Cost of bug-fixing
Conceptual integrity is the most important consideration in system design.
Errors get exponentially more expensive to fix as development progresses. A mistake made during the requirements phase would typically cost factor of 100 to fix if it survives to the operational phase.
Most bugs have to be fixed eventually — The earlier it is caught, the less it will cost to fix.