> Firing on timeout is not the ideal way as the general pattern tells us people open multiple tabs which they may or may not read.

This is what I was thinking. I do this all the time. However, I have to question your statement all the same. Yes, this is something I do. But, I'm a software developer. Assuming that the general population of internet users follows my personal usage patterns would seem to be a bad idea. Being a web analyst, are you saying that you've conducted studies verifying this pattern?

Regardless, triggering based on scroll seems like a sounder approach. Thanks for the pointer.