project profile configuration

Dears,

     I am now working in a construction project, every project have more than 100 WBS element.
i am now configuring the project profile and i want to know how can i decide to make :
network assignment to project definition to be only 1 network for the project or network assignment to WBS element to be 1 network for every WBS element ?
How can i decide to use one of these two options ?

thanks in advance