pen size doesn't always dictate how many will survive in a pen together or tolerate each other..Somtimes its acceptable to them and others times not meant to be.
my mature bobwhites(4-5 year olds) don't tolerate extra hens or cocks in there pens. they are pair bonded. Each pair have a 3x3 or 3x4 pen, real cozy and plenty of room for pine branches and small roosts in for them, plus each pen gets a small 12"x12" sand box to dust in..
now my younger ones i can sometimes get away with colony breeding (3x8 pen) within the first and maybe the second year, but not always and normally within there second year its old news and the battles will start, it is quite brutal if not caught in time... fights will break out between males and males, females and females, that happens in wild as well, the only difference is in pens they cannot get away from each other., breeding or not bobwhite will fight.
Charlie