I went through others' comments. I learned so many things. However, I want to give my opinion. 

In my opinion, a project manager must not have all the knowledge about the project. PM may manage so many projects. Therefore, he may not have all the knowledge. 

However, a project manager must have good and clear knowledge about whats going on in a project. He must take updates from team members. From experience, PM can give valuable suggestions. 

PM can make decisions from his experience. On the other hand, he may meet with other team members and discuss the challenges. Then, he can take the necessary steps. I don't think a quick decision is wise. Before taking any decision, there should be a dicussion. On the other hand, if the PM has enough knowledge, he can take time and think. then he can decide. However, I highly recommend discussing and taking opinions from other team members too. 

Ensuring that I provide the most complete and robust solutions to my team, even with limited time and contextual information, involves a multifaceted approach. First, I would prioritize establishing strong communication channels within the team and management. This ensures that I can quickly gather diverse perspectives and relevant information when needed. I would also invest time in developing a deep understanding of the project's objectives, scope, and potential challenges, which allows me to make informed decisions even under time constraints. Additionally, I would rely on a combination of project management tools and methodologies that enable agile decision-making and flexibility. Leveraging the expertise within my team is crucial; thus, I encourage open discussions and brainstorming sessions for collective problem-solving. Finally, I would make it a point to continuously learn from past decisions, whether successful or not, to refine our decision-making processes over time.