Carefully designed teams are essential for lean start-up because they determine how effectively the method is applied and how much value is delivered to customers and stakeholders. 

The method involves learning, experimenting, and adapting based on hypotheses and feedback. The team composition can affect how well they embrace and use the method. For instance, diverse educational backgrounds can enrich problem-solving, but few members may initially resist learning by doing. 

Teams also need to collaborate and communicate well internally and externally, and align their goals and actions with customer needs and expectations. Teams also need to be agile and flexible, and willing to pivot or persevere based on evidence. Therefore, teams need to balance their strengths and weaknesses and cultivate a culture of trust, transparency, and accountability.