How much time should be allocated in Design part of System Development?
It depends on the strategy. If you are talking about a typical waterfall type process, perhaps up to one third of the time is spent on design tasks such as developing use cases and specs. The latest trend in system design is towards processes that do away with all the up-front time. The most popular new school of thought is Agile Development. Basically, you begin by writing user stories instead of full blown requirements. These are prioritized and the team begins building right away. They build in two week sprints with the goal of producing executable code that can be demonstrated.
