Decisions under pressure are not easy. Some will not know how well they will do till a SHTF time were they are under all types of pressure. They may do good under some pressure and bad with other types of pressure.
Someone that you know dieing in front of you is one type of pressure and another type is finding food or water for your family. Another is being shot at and can you keep cool so you can shoot back. There are so many types of pressures that can happen in a SHTF times.