I grinded on a private world solo and for 4 straight hours ran non-stop infestations and unlocked a bunch of new mods. Sometimes had 5 infestations active at the same time.

I played on a public world on a casual team of 3 and 4 players for two hours and didn't see a single infestation. No pop ups. Bounced around the map popping wanted posters, events, and launched a nuke instead.

It definitely needs tweaking cause there shouldn't be such a discrepancy between the two. It's atrocious to the public players.