The title of this question says it all but I will elaborate a little bit. I am trying to find out : 

1. How often does AS 7 Nodes publish the load metrics to the mod_cluster sitting at the Web Server ?
   
2. Is it configurable ? or is it part of the server side advertise frequency ?
3. Can there be a scenario that the Node doesn't publish or advertise in time due to heavy CPU usage at the Node resulting in mod_cluster at the web server considering the Node dead ?
4. How long does the mod_cluster at Web Server wait before declaring the Node dead due to lack of communication ? Again, is this configurable ?
   

I do not think #3 would be of any concern as heartbeat would be sent as soon as the Node is eased up on processing causing the mod_cluster to recognize that and start serving requests.

One or more of the questions listed above may be been asked and answered elsewhere, if so please point me to those links.