You will notice that prolonged period with people that are not very close to you when you are under the hard condition (SHTF) will add much more pressure to you.
People act different under the pressure, you may know someone very good, live with him for several years, and then one day to find out that you do not know him very well, he (or she) may act very different then you are expecting under hard conditions.
Good practice is to train that with your folks, I mean you can not have real conditions, but having camp trip can be good way to find out what you and people around you need to work on more.
About company when SHTF good thing is to consider the thought that family or group is usually not meant to be some ideal kind of democracy.
It is good to know exactly who is in charge and who is who.