Don't know if you're still interested in an answer to this, but we also maintained history cards for each box. Based on the system you use, changes may or may not carry over each year, or as system vendors change. It has happened that the box history has been helpful if a relative has found a key and can identify that the key belonged to a box at your bank - which was closed 10 years ago. Or drilled.
I believe it's a bank procedure, however, and not required by an regulator that I'm aware of.
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Opinions are mine and never to be taken as legal advice!