Claims get delayed for boring reasons. Not fraud, not disputes. A family that knows a policy exists and can't find the carrier's name.
Keep six things. The policy contract itself, which is the full booklet the carrier sent at issue and not the cover letter. The original illustration from issue, so you can compare against it later. Your annual statements, at least the last three. Any loan documentation, showing amounts and dates. The beneficiary designation confirmation, which is a separate acknowledgment from the carrier rather than the application page. And one sheet of paper with the carrier name, the policy number, the claims phone number, and your agent's contact information.
That last sheet does most of the work. With a policy number and a carrier name, a beneficiary can start a claim in one phone call. Without them, they're calling companies at random or waiting on a state unclaimed-property search that can take months.
On where to put it: not only in a safe deposit box. In several states a box can be sealed on death until an estate representative is appointed, which is exactly the delay you were trying to prevent. A fireproof box at home, a folder in a filing cabinet your spouse knows about, or a labeled envelope with your estate documents all work better. Tell at least two people where it is, and one of them shouldn't live in your house.
Digital copies are fine as a backup and poor as the only copy. If everything lives in a password manager nobody else can open, you've built a vault your family can't get into. Scan the six documents, put them somewhere shared, and make sure the beneficiary knows the login situation.
Set a reminder for the same week every year and fold it into your anniversary review. Confirm the beneficiary is still who you think it is, file the new statement, check that the contact sheet is current. Fifteen minutes, once a year, and the difference it makes shows up on a day you won't be there for.