It depends what I am carrying, what I am wearing, and where I am going. Most of the time when I am just out and carrying my PT145, I don't have a spare on my person - the thinking being that I am not putting myself in a situation where I would need to fight off an army in order to make it to safety so spares are in the vehicle. If I am going to be somewhere that I don't feel quite as comfortable, either due to environment or time of day (say having to go to work for a downed server at 2am or something), I have a spare in my offside pocket. If I am carrying my 1911 in my shoulder rig, I have two spares in the offside pouch regardless of time or place.