[bob_roboto]

Not necessarily. Granted, you obviously need to make a network call at some point but you can host the entire experiment configuration in a file that is served through a CDN and the mobile client only needs to download it once (and it can be cached however appropriate for your use-case). The client SDK can then use the file to derive the experiment configuration by passing the required parameters to determine experiment allocation into the SDK which can then compute without further network calls.