But saving all that data just seems like overkill for most home jobs.

What kind of stuff do you think is behind Archive 7? My first thought was old train schedules, but that's probably just my boring life talking. Your key idea is great for a story. Maybe the key feels warm in your hand when it's near one of those wrong doors. The real trouble starts when a door appears somewhere totally normal, like in your own hallway, and the key just fits.

Learned that lesson the hard way with a new pack of light bulbs last week. Screwed one in, flipped the switch, and it popped like a firecracker. Scared the cat half to death. Now I've got a closet full of bulbs and trust issues. What's the worst thing you've ruined by not testing it first?