Privacy wise it makes no difference if they read your contacts once a day or once a minute. If the want, they have your contacts either way. Actually this is a

Privacy wise it makes no difference if they read your contacts once a day or once a minute. If the want, they have your contacts either way. Actually this is a hint that they actually might not store your contacts names, pictures, addresses etc in their own app, but only retrieve that information to display it. The way their web client works (it communicates with the smartphone app, not with the whatsapp servers) is another hint that they might not even store your full contacts on their own servers.