All team members have their own roles in the project and should be responsible for different parts of the work.
- Developers don't have the ability to see the whole picture so deeply at the beginning. So it will be hard for them to see bugs in the documentation or in the code. Especially in the active development phase.
- Neither the developer nor the manager has software testing skills and experience. As a result, they can miss important bugs that will be found at the end and make the project more expensive.