My rational, not based on any facts at all, is i want to be prepared for 3 attackers, 3 bullets each. in my mind, this is a worse case senereo i want to be prepared for. my wifes firearm, (shield) holds 9 rounds. while mine holds 17+1 rounds, i feel comfortable with 9.
issue, i only have 17 defense rounds
17/2 != 9