People update their will and assume everything follows. Registered accounts and insurance policies do not — they pay to whoever is named on the designation.
Where things go wrong
A former spouse still named on a policy from a previous decade. A parent named before children were born. An estate named as beneficiary when a named individual would have been simpler and faster.
These are not complicated problems. They are simply invisible until they matter, at which point they cannot be corrected.
What to do
List every registered account and insurance policy you hold, confirm the named beneficiary on each, and check that it agrees with your will and your current intentions.
Repeat the check after any marriage, separation, birth or death in the family.