I'm not completely sure this is on topic. I apologize if it's not.
I have a 24-word seed stored (etched on metal) in my house. I continue to worry (just a little) that the metal might either fail to survive a fire or end up buried under so much rubble that it will be outside my control. So I'm using a backup storage system, and my question is whether it is insecure in ways I haven't thought of.
Namely: I have a Trezor (with the same seed and with a PIN number that I am confident is quite strong and secure) buried a few inches underground in a waterproof box, on my own property but quite far from the house (and so presumably safe from house fires). I can imagine that somebody might stumble on this somehow one way or another, but in view of the strong and secure PIN number I am not concerned about this.
I ordinarily walk by the burial site a few times a week, so will notice if it's been disturbed, in which case my plan is to bury a different Trezor, possibly in a different location.
It's also possible that the waterproof box is not as waterproof as I think it is, but I expect that the likelihood of losing both my metal seed backup to a fire and my Trezor to the elements is acceptably small.
I could, of course, put that Trezor in a safe deposit box instead of burying it. But I am imagining a scenario where my seed phrase is gone; I'm not sure whether it's been destroyed or found by a firefighter, and I want to move my coins in a hurry, possibly on a weekend and surely without having to spend time at the bank.
Is this plan less safe than I think it is? And if so, can you suggest an alternative that addresses the same issues? And finally, am I worrying too much about extremely unlikely events and not enough about others that are more likely but that I've failed to consider?