Yeah, I’ve noticed the “gangs of three to five juggernauts” effect happening on a recent build too, though I’ve not been playing a lot the past week.
I had a mansion whose first floor had, I think it was, three juggernauts, a brute, and like five other miscellaneous zombies. As if a juggernaut had casually embezzled all the spawn points that should have gone towards filling the place up and gave it to his cousins instead.