I can't figure out, how my robots select the recharge Roboport.
Let's say i have 200 construction robots and they have to travel ~150 tiles crossing other roboports. All of them just use just the 3 closest ports to the construction area. So sometimes 20 of them wait for a free charging spot, because only 3 ports are used to recharge. I'd say it would be more efficient if some of them fly back to a more distant port to recharge.
I know i can place more ports near the construction area, but how can i figure out the range they use to recharge? Is the condition, that the recharge ports area covers the build/delivery area?