Checkpoints: Implementation Model

Interfaces and dependencies between components have been defined.
The workload for the Implementation Team is balanced; potential bottlenecks have been identified and work has been redistributed, and contingency plans have been created to allow critical work to be redistributed if the initial work allocation becomes imbalanced.
There are no instances of dependencies crossing more than one layer boundary.
Unnecessary dependencies on lower-layer components have been eliminated.
The impact of necessary dependencies on lower layer components have been reduced by letting components in middle layers re-export interfaces from components in lower layers.
The number of layers is no more than seven (plus or minus two), or there is a well-understood reason why more layers exist.
The ratio between the number of packages or subsystems and the number of components is consistent with the application size and complexity (for example, 5 packages or subsystems and 1,000 components is a sign that something is wrong).
The amount of source code is consistent with the expectation based on the number of design classes (for example, 100,000 lines of code for 10 design classes is a sign that the either the design or the implementation, or both, may be flawed).
The actual implementation effort is close to what was estimated, or if not, the basis for estimation has been examined and adjusted.

Rational Unified Process