Think through your most likely scenario for using it, in your environment and situation, and test it that way. What events would cause you to use it? Where would you go? How would you get there? Can you live out of it with no other support for 72 hours?

If the scenarios you envision require foot movement over a long distance, hike that distance. Do you carry enough water for 72 hours or do you need to purify it? If so, practice that as well.