Why is there a need to generate more than one high entropy seed? It would seem like if the original source of entropy is high quality, than some 512 bits should be more than enough to seed a CSPRNG which has no strong (or known) weaknesses, and pretty much endlessly generate new random numbers and re-seed itself. The average user needs very few cryptographically strong random numbers over the life time of a computer, almost surely (<106) will be enough for all of said users potential applications.
On the other hand reading about cryptographic RNGs / encryption as some one that deals with them occasionally in code, and knows a bit of math, (but not highly technical literature by any means), one gets a highly disjointed sense of what people consider correct seeding procedure, how often a seed should be re-used,
Would re-seeding to generate some 106 random bytes really be enough to find a weakness in CSPRNG and in such a way as to make the original entropy source weak enough to regenerate it with a human lifetime?
I'm not sure if this is more of a Math Stack Exchange or Stack Overflow question. But I would really like to see some mathematically / logically convincing guidelines. I can reference some specific CSPRNGs (but I'm not sure whether that helps or hurts the discussion).