I shoot only with a Sinar F2 4x4" and only have children (age 4-12). I have actually very little out of focused images and maybe that is because of:

1. I use the same models over and over, so they are used to it. And know the important of standing still.
2. I usually shoot waist up. But I have a couple of headshots
3. I shoot outdoors during summer so often I can have f-stops like f8-f16. and speeds like 1/60 It's not much, but with a tripod it's enough.

OT! One plus with LF is that it forces one to really slow down and I usually during a session shoot 10-20 photos where one quarter is really good one that I print in my darkroom later on.

/ Marcus