There is an entire crowd source science around how to churn and different companies have different policies.

For instance signing up for business cards using your SSN as the EIN doesn’t show up on your credit report.

Once you have one card from Amex, they don’t do a credit pull for additional cards. Between personal and business, Amex has six Delta cards and four versions of the Platinum.

That means you can apply for as many Amex business cards as you want with no effect on your credit.

Chase has a hard 5/24 rule where you can’t have opened more than 5 cards with any issuer within 24 months. But that doesn’t include business cards.

You also have to space credit card applications out. It also helps that I have a long credit history. I opened my first card in 1996.