I once heard that Runescape "ticks" every 0.3s, and that seemed like a very long period of time, although Runescape is kind of a slow game.

I'm building a more dynamic top-down shooter game, and I'm wandering, how often should I communicate with the server? ASAP, or every 0.1s? How do shooter games usually do it?

Both the server and the client are written in Javascript, node.js and socket.io are being used.