An old army trick is to have people hold up their two most important pieces of gear as they march by. Just be sure that scanning what people hold up you stay alert enough to spot wiseacres. Instead of holding up the poncho and entrenching tool a buddy help up a large pouch of chewing tobacco and a flask of spirits. Sarge was so glazed over he missed it.

Buddy checking also works. Broken into small groups one checks the others. The threat is that if anyone in the group doesn't have the item the leader has to give up his/hers. Gets interesting if you are talking about parachutes.

Gear-inspection laid out in front of each person is an option.

All that said there will always be people who don't cover their bases. In any large group there will always be failures. Leaders are prone to failures as they get make sure everyone else is prepared and overlook their own situation. A good second in command makes it his business to check number one's gear and will be sensitive to the areas they tend to overlook. Training and due diligence can reduce the rate of failure but it will never eliminate it entirely. Part of the human condition.

Given an average set of people and reasonable levels of diligence a failure rate of two percent is a common working estimate. With close to 200 people with limited experience I'd figure at least four to eight people with issues. Half of those will be on the order of being brain-dead incomprehensible.