I am still working on my gear, but I try to avoid duplication while ensuring redundancy. Because I think the various kits have very different purposes, I try to let the purpose of each guide what is in each.

At the same time, I want each kit to salute the Rule of Threes (you may die if you go: 3 minutes without air, 3 hours without shelter, 3 days without water, 3 weeks without food) and whatever functional categories you think are appropriate( mine include: First Aid, Shelter, Fire, Water, Food, Navigation, Light. Signaling, Self-protection, Hygiene, and Morale).

My situation is such that I have working prototypes of:

TSA-complaint EDC in my pockets.

"Outdoor EDC", including PSK and PFAK stuff that is not TSA-compliant, to add to pockets and hang from my belt.

BOB in a medium hydration backpack, generally intended for fair weather travel, with winter weather extensions phased in as winter begins.

Car kit, which includes my BOB, plus a stash of gear, food, and water.

Bug-in stash at home with more gear, food, and water. Included is a cold weather BOB type array of gear, food, etc. If I had time most of this could be transported in a vehicle-based bug-out.

Each level of kit contains progressively additional and more sophisticated stuff, that also adds redundancy.