Custody doesn't fail because you did something wrong at the start. It fails because the conditions you designed for don't stay fixed.
Every custody architecture rests on assumptions: that certain people remain available, that certain locations remain accessible, that documentation stays accurate, that software and hardware remain compatible, that your own memory and habits stay aligned with the procedures. Over time, those assumptions drift. People move. Relationships shift. Backups age. Devices go out of support. You forget a step. You take a shortcut. The gap between how the system was designed and how it's actually operating widens. That's decay.
Decay is structural, not moral. It doesn't mean you were careless. It means you're human and the world is dynamic. Custody systems that aren't actively maintained will decay. Not might—will. The only question is whether you catch the drift during a scheduled review or discover it during a crisis.
Why does custody decay in practice? First, familiarity fades. When you set up your system, the procedures were fresh. After a year without needing to use them, the details blur. Your co-signers forget what you showed them. You forget which backup is where. Second, the environment changes. Software updates. Hardware gets replaced. The wallet you documented may have a different UI now. The "secure location" may have been re purposed. Third, operational discipline erodes. You skip a step because you're in a hurry. You make an exception once, then again. Each exception becomes a new normal. The architecture on paper and the architecture in practice diverge. Fourth, life changes. Everything in the previous paragraph—relocation, scaling, family change, health—alters the assumptions your custody was built on. If you don't re-validate after those changes, you're running on a design that no longer matches reality.
The countermeasure is not more initial effort. It's ongoing validation. Cadence. Periodic reviews that ask: Do our assumptions still hold? Can we still execute recovery? Have we drifted? Custody that is not reviewed will eventually fail. Decay is the default. Maintenance is the only way to keep the system aligned with the conditions it must survive. Treat custody as infrastructure: design it well once, then maintain it for as long as it matters.