That has been exactly my experience with a very minor event a few years ago. The bills kept coming at random intervals for about 18 months, some for a few tens

That has been exactly my experience with a very minor event a few years ago. The bills kept coming at random intervals for about 18 months, some for a few tens of dollars, one or two for hundreds, others for literally $0. I just had no visibility into it and honestly would only be half surprised if now, 8 years later, I received a bill for $17 for procedure AU8-QB-12 from department CO9-s4 (and the bill would mention that my insurance paid the other $872)