I have found differtent sites and different countries have different update times.
Some of the US ones are 1 second updates, some are longer. The london ones average about 5-8 minutes, and some are longer.
Bear in mind if your cameras update in 1 second intervals and you set the delay to 1 sec, it's going to kill your CPU and probably slow RR to a crawl.
In others words you have to get a nice balance