I carry three keys only. One each for my cars, and the house door lock key. Everything else, has a place on the wall to hang the key.
In my entire life, I have never had to go look for my keys as they are in the ignition, or in my pocket. On our two week trip to Alaska my keys were 100% useless as they would not fit anything for well over a 1,000 miles. When I stand up, I always pay my pockets and kinds freak if I don't feel the lump for the keys.
Never once needed to replace a battery!
I have set my phone down in the car and gone inside or left it on the garage workbench. Never left it behind, or forgot where it is. It is indeed my second brain. I lived most of my life with no cell phone, but I can't imagine life without it now.