Any project can optimize whatever factor of "quality" it wants to. In optimizing any one factor, other "quality" factors are generally denigrated. In a landmark experiment conducted by Gerald Weinberg and Edward Schulman, five teams of software developers where given identical requirements, but each was told to optimize something different: development time, program size, data space used, program clarity, and user friendliness. In all cases except one the programs produced by the teams where rated best in terms of the attribute they were told to optimize.
If you tell your people that everything (such as schedule, size, maintainability, performance, and user friendliness) is equally important, none will be optimized. If you tell them that only one or two are important and the rest unimportant, only the important ones will be addressed. If you give them an a priori relative ranking, the ranking may not be appropriate in all situations on the project. The fact is that there are trade-offs -- different trade-offs -- to be made constantly during product development. Work with your employees and help them understand your priorities and your customers' priorities.
Reference:
Weinberg, G., and Schulman, E., "Goals and Performance in Computer Programming," Human Factors, 1974.
