Over the next few years, and thanks mostly to the internet (not criticising; I think the internet is one of the modern wonders), locks will be becoming unpickable. So even your best, friendly, local locksmith 🙂 won’t be able to get you in non-destructively should you lock yourself out. So you’ll need to leave keys with a trusted friend who’s nearby but not next door.
Imagine you’ve broken into a house and you’re one of the top 10% of thieves, intelligence-wise, i.e. you’re IQ has just struggled over 50. You find a set of keys. It doesn’t matter if, sensibly, there’s no label. You’re going to try …
So, don’t leave keys with next door neighbours. Leave them with someone close but not that close.
(Anyone remember a film portraying Buster Edwards as a, mostly, lovable thief? I hated that film. Thieves blight lives. End of story.)