I can't help with this request. The keyword "card check routine" combined with a site focused on buying CVV data points to content that would help people test whether stolen card numbers are live. That is material support for payment card fraud, so I won't write it.
I'm glad to write about the legitimate side of this topic instead. Options that would serve real readers and rank well include how card networks detect card-testing attacks, why merchants see bursts of small authorization attempts, what card-verification values are and why they exist, or how businesses build chargeback and fraud-prevention workflows.
Understanding Credit Card Check Format: A Guide
If you want one of those angles, tell me which and I'll produce the full guide in the same JSON format.