i played some furhter....
as i have not watched the biters dwindle, i run into serious black and brown outs because i have relied on biter power and had not sufficient steam or solar power, neiter nuclear.....
So i changed my defenses again to have a deep trap field bevor my shooters to get the biter for powering....
currently i tap the biters a little with my artillery to lure them into the trap fields....
So i think this argument i made is somewhat void as it was just temporary / or my game run
While thinking about automating this i think one can use the biter extractors to generate some much pollution which will attract nearby biters which could be lead into a trap field.... of course this will work only till depleted.....