It is crucial for product manager to make the team works fast and delivers quality product. There are many reasons that might interfere with an ability to meet their deadlines:

• There are many difficult puzzling questions that appear as a problem to be solved in development process. A team spend many hours to find a solution but still the result don’t meet users needs.
• Threats would appear if developers don’t understand customer’s needs. There are new requirements all the time. Programmers have to change the interface on the fly, add new tasks.
• Difficult requirement might trigger problems. If tasks are written only in text and are difficult to understand it would slow down the working process because programmers spend too much time to apprehend requirements.
• If a team has no designer, programmers should prepare graphic by themself. They should distract themselves to use graphic editors.
• Customer gives bare requirements and information about users’ needs. Programmers work blind. It demotivates a team and slows down development.

• One of UX designer’s task is solving difficult problems in interface. He could make suggestions, test them on prototypes and give the best one to programmers.
• A team could estimate their affords correctly only after proper usecases research and UX tests. It is necessary step for understanding amount of tasks and setting up real deadlines.
• If agile/scrum method is used UX/UI tasks should be done before front-end and back-end. UX prototypes help programmers watch the task in visual form. It makes them easy to apprehend requirements.
• Many programmers don’t like to work with graphic editors. UX/UI designer could make them work with coding tasks 100% of their time.
• Skilful UX designer could create useful and understandable interfaces without customer’s feedbacks. It could help if there is bare requirements in a project.