To ensure you get the best possible results from your bot or automation rule it is important that you always have the most up to date prices for it to react to, without this a rule may not always trigger.
Just like any of the main trading screens Guardian has its own refresh rate which you can set while on the 'Market' tab of the main guardian banner.
If you have 'Streaming' enabled in your main settings then guardian will be able to refresh markets as fast as 20ms. If your still using the older 'Polling' method to retrieve the latest updates then the fastest refresh rate will be 200ms
For full details on how Guardian cycles and refreshes markets and how this effects automation and some example on how best to set up guardian please see this thread from our forum