It depends on how they do it. In my case I had a DB on my computer with thousands of cards. They could have used those cards as part of my sentencing but didn't

It depends on how they do it. In my case I had a DB on my computer with thousands of cards. They could have used those cards as part of my sentencing but didn't. Instead they tried to estimate losses based on cards they believed I used. I don't know if it was correct but it seemed like a more reasonable way to do it.