There are now 5 different subscription methods: not at all, subscribed without notification, subscribed with instant notification, subscribed with weekly notification, and subscribed with daily notification. You can change the default in User CP > Subscriptions, and you can change subscription for any subscribed thread here as well. I just wish there were an easy way to change it for all subscribed threads. I have stopped using email notification to see new threads.
Just so we're all clear, it will send out a notification if you visit the board at all, even if you don't visit that particular thread. So if you have instant notification on for such and such threads, as soon as you visit the board all will be reset and you will receive instant notification of new responses to any of those threads.