At work we use a central
NuGet.config file to configure additional NuGet repositories for all developer Machines and the CI-Build environment (see Chaining multiple configuration files).
Further we define a common folder which holds all downloaded packages (defined in line 7: “repositorypath”) for all solutions in our code repository (see Specify ‘packages’ Folder Location).
nuget.exe as well as Visual Studio use the defined repositories from that configuration file when placed in a parent folder of the solution.
Here is a sample file as a gist: