The post is designed to give you an understanding of how you should write your rules if you aim is to do many things all at once across a number of markets.
Say you have Guardian refreshing at 1 market per second and you've got it cycling round ten markets, then you are retrieving new price information for each market once every ten seconds.
The automation rules are tested each time new prices are retrieved from betfair (to ensure the triggers are based on current price information), so for this example you should allow each rule to stay active for at least ten seconds (probably 15 seconds to be on the safe side).
If you've got 30 markets loaded into Guardian (with a one second refresh), then you'll be getting new prices for each market once every 30 seconds, so you should increase the time the rules stay active accordingly.
If you are not trading manually with the Bet Angel trading screens, you could afford to increase Guardian's refresh rate and still stay within betfair's 20 calls per second data request charging threshold. Obviously if you're refreshing Guardian every 500ms, you'll cycle round 30 markets in 15 seconds.