The limit is per depositor * bank, not per account.

Per person, per bank, per account ownership category.

https://www.fdic.gov/resources/deposit-insurance/brochures/i...

If you had a single-owner account and a joint account, you would have $250K in insurance for each of those accounts.

You’ll just be the depositor four times, once per account. It’s per account at the end.

No... if the same depositor + ownership structure owns 4 accounts, the total insurance is $250,000, not $250,000 x 4.