I always thought per account
Per type of account.
CMIIW, but my understanding would be:
A and B are married and have kids C, D, E, F, G and want $3.5MM insured.
Account 1 is under A's name and has $250K insured.
Account 2 is under B's name and has $250K insured.
Account 3 is a joint account for A and B and has $500K insured.
Account 4 is under A's name and has POD beneficiaries names as C, D, E, F, G and has $1.25MM insured.
Account 4 is under B's name and has POD beneficiaries names as C, D, E, F, G and has $1.25MM insured.