Whenever I think of this problem I figure it would be best to have a key that you split into N parts and give it to N people you trust. That way if you're gone they come together and unlock it. More secure because if any of them is individually compromised, your information is still safe.
That also means higher risk of failure, doesn't it? If just one of the N people isn't able to attend for whatever reason, your stuff is gone for good. If I give the key to my spouse, they can just use it. If I give it to 5 people, chance, one of those is unreachable when I'm gone, is 5 times as high.
That's why there should be another parameter: you should split the key into N parts so that any M <= N can open the lock. You can increase M adding people you don't trust 100%, say to 8, but leave N at your comfortable level, 5. Even if those 3 conspire, they would still be 2 people short of being able to break the lock.
You can do 12:5, give 5 parts to your spouse and spread the remaining 7 among your relatives and friends. There will still be a single point of failure, though, if somebody steals all 5 parts from him/her. You can decide to decrease allocation to only 4 parts so that your spouse would need to cooperate with any of the other trusted parties.
The point is there is enough room for designing a scheme that is both secure and reliable.
