Supposedly, every simultaneous hit on the mini-asteroid counts, so the more you hit at once, the more hits get processed. Thus, more ore in your cargo hold.
Yes , it is true that more mining lasers hit in same time , better mining ratio .
But in Kamome case , turrets are placed in 2 front , 2 behind and 2 more behind , so max of 2 can hit at same time at front , unless you mine in turret view and fire only up or down with all 6 , which is not easy .