I'm subscribed to a few playlists that are updated fairly frequently. Some are every day, some a few times an day. If I don't log in to spotify for a few days (ie, over the weekend since i'm a 9-5 listener) I might see 20 notifications that Playlist X has had 1 or two songs added. Why not change it so that it consolidates them all while you're logged off, and simply tells you "User has added 35 songs to playlist X" .. or something to that effect.
Please bear in mind that the Community is not an official Spotify support service. It's a place where we all help each other, whether we work for Spotify or not. So please use your discretion when using the forum.