Hi Khanh,
You can take either approach with your project, both approaches have benefits and drawbacks. For example, if you were to choose one site which doesn’t end up being the hub, will your design be flexible enough to be implemented in another location? However choosing a specific location means that you can narrow in and think more practically about your proposal’s design and implementation.
There is no right or wrong answer for this one, just whatever you think is most appropriate for your team as you progress through your project.
Let me know if you have any other questions!
Rachel