I'm fairly certain this is also incorrect. If you have a credit card attached to your account AS WELL as a bank account, only then will PayPal pay the seller instantly because they know they can always snatch from your credit card if your bank account doesn't come through.
That is true, a transaction where funds are drawn from a bank account is otherwise known as an echeque and may take days or even weeks to clear. This is why sellers dislike it and another way ebay is trying to steer people towards credit card funded paypal rather than bank direct deposit.
If the account is funded by a credit card then it is instant.