Servers will be tested every minute by default. (You can change this in the Prefs tab.) You'll see the timer counting down on the AutoTest button. If you can't wait until it reaches zero just click the button and it will test them right away.
There is a thirty second timeout on all http and https connections. You can change this in the Prefs tab too. The idea is that if your server is taking more than 30 seconds to respond it's either down or needs someone to take a look at it.
Important Note: One test every minute is 1440 tests every day. If you use one of the free hit counters that have you place an image on your pages this won't affect you but it will affect statistics generated from server logs unless you have them ignore the computer ServerWatcher is running on. If you just do a ping test it will never show up in your page hits because it's poking the machine itself not requesting a web page.
