What many people do not realize is that most charged-off debt is uncollectible. Only a small fraction actually gets paid. Most debtors cannot be located by their collectors, and that's the primary reason why debt collectors will normally settle for less than what is owed.
Checking your own credit doesn't show up on the credit report collectors pull, so they would have no idea you did this. It also costs them money each time they pull a credit report, so they're unlikely to do it very often (or at all) by the time the debt is old enough that it's unlikely collectible.
In the same way that a debt validation letter is a "smell" to the debt collector that the debtor is concerned about their debt (and potential credit status), any indicator that the debtor is evaluating their own credit can also potentially raise the debtor's file with the collector to high-attention (or litigation) status (versus being sold off to another collector).
This is not the same thing as checking your own credit, which is not visible on reports that creditors see.
https://www.experian.com/blogs/ask-experian/credit-education...
Copays are typically (though not always) paid at time of service, not billed after-the-fact. In any case, it takes a long time for a bill to become overdue and get sent to collections; before that, it won't show up on your report at all. Having 20 different overdue bills (of any sort) in collections is definitely an objectively worse sign of creditworthiness than having a single active loan of 20k of any nature.