I stand outside the door and do this check as I tap my pockets. When I do not need my wallet it always messes me up. Wallet, keys, and mobile. Wait wallet (don't need it) and move to keys, but I have my hand on my keys and try to remember why it is okay not to have the first item. It takes a couple minutes for me to realize it is okay to shut the door as I have my keys and I can go back in and get the other items. I have tried to change the order of the taps or checks, but in three years it has not taken hold.