Why pack for 72 hours? What is so special about that number? In the event of an emergency, it would require AT LEAST 72 hours before governmental forces could be mobilized to feed you and your family. FEMA has even suggested that families prepare a TWO-WEEK kit. In a wide spread major disaster, it could take that long to get things organized. For example, after the big quake in California in 1989 it took 12 days for relief efforts to reach some of the residents.
It would be a good idea to test your kit several times until you feel totally comfortable and assured that you could really live for three days with no other items in your possession. My family takes them camping, as both a test and refining exercise.
You may want to test your kit by planning to stop using the gas, water, and electricity in your home for one to three days and use only the items you have in your kit. [Do NOT turn the utilizes off for this exercise, just don’t use them] When you feel comfortable with this, it would be a good idea to go camping with your family and take only your 72- hour kits (no other camping gear or supplies/provisions allowed). Be sure to walk, carrying your kit, a minimum of two or three miles or more to be sure that in the event of an emergency you could really carry it as far as needed.
IF you can not carry it that far, it is WAY better to know that now instead of discoving it during an emergency.