I am always in the same truck with the same partner, but I share it with other people on the other shifts.
I tag all the cabinets, jump bag, etc with numerical zip-tie style tags. I tag every compartment of the jump bag, intubation kit, literally everything. I write all my numbers down, and the next time I'm on I go through and compare tag numbers. If it's the same, I know everything is there. If it's a different tag, I open it and re-check. Often, stuff is missing because someone used something,didn't re-stock for whatever reason, and put a tag back on to appease me. I'm really the only person that does it, but I just like knowing where everything is. I go through every thing again at the end of every month to look at expiration dates.