Your numbers already did show that in games I'd play (some 30 planets per player) one 75% "breeder" would be sufficient to pop all the reds I'd expect to get in my share of the universe.

OTOH when those conquest give me lots of planets, then I start hitting RL and Stars! hard-coded limits, and colonizing reds just compounds them.

Please do add a TL/DR for mere mortals.

BR, Iztok

The genius of science, to ask the right question so obvious that everybody wonders how could this have not been asked ever before.

This is generally the best use for pop. Any PRT, not just IS, can benefit from red planet colonization. IS are a bit better in that they can grow pop to replace red-planet losses without having to lose productivity on their green worlds.

As for whether to overpop normal worlds or do red planets - reds are a much better deal. Overpop on a normal world will quickly get to 1.5% losses, or 3.0%, etc.

The only real problem with red planets is that there aren't enough, assuming a reasonably viable race design. A single 100% planet can grow enough pop to keep ~20-30 reds topped off. But nobody plays races with ~1/20 greens after terraforming.

What's TL/DR?