In flats it's usual to have a fire door as the main entrance which will have a "thumb turn" lock on the inside. No key needed to lock or unlock it. I leave my keys in the kitchen.
My window key is on the windowsill, the patio door key stays in the door and my front door has a 'thumb turn' thing. My front door and car keys are in my handbag away from the front of the house and car. Like Vagus I don't want my car stolen by some oik with a gadget. Mind you I drive a Fiat Panda so that's probably a deterrent anyway!
The front door key sits on a piece of furniture just inside the room next to it. The back door key is on a hook in the kitchen. All window keys are in dishes near to the windows but out of sight. Car keys are in handbag.
Much of my childhood and youth was spent miles from anywhere in Mayo or five miles from the village in Kerry.
Doors were never locked and often in Kerry I'd come down in the morning to find a sleeper on the settle. Weary from his long walk or cycle from the pub he'd come into our house and go to sleep.
I've got back into that way now and I love it.....Dave isn't so keen! :-)