Every Few Decades
Something was bugging me about Calvin's logs so I had to listen to them again.
"Back in the early 90s, Stein Lightman died. Every 10 years or so, we send him into xm exile for a while. We forged documents of a marriage and eventually a birth certificate. And when the fictional Lightman jr would have been in his mid 20s, we unleashed his simulacrum into the world, as far as the world is concerned, the Lightman genes produce a long line of nearly identical offspring. But in reality, every few decades, Lightman assumes the identity of his own descendant."
How did they know this was going to work?
Let's suppose the early 90s is around 1993 and Lightman was 25 years old when Warhata happened. In 2003 Lightman would have been 35. It is not out of the ordinary for someone to look 10 years younger than their age. Look at Dick Clark, for example. And maybe this is when they start forging marriage and birth certificates. But even if it is, this Lightman "jr" would only be the first "born" to LIghtman's "wife." Calvin is talking like this have been going on for decades. I don't see it based on the current timeline.
Unless he's speaking in assumptions and theories