Doesn't this also depend on natives' "ferocity" value in that province? Or is the 5% damage per point too small to matter with stack of 1k?As an aside, if you find yourself colonizing anywhere that has around 1k natives or less, a stack of 11 at minimum maintenance will insta-wipe any natives that pop, with no causualties on your side (this is especially prevalent in N. America). I find myself doing this whenever playing a New World native after “unifying” my starting area, just to pass the time until Europeans show up.
As @DDRJake says, always get your ten-to-ones.