How Is Ortho Insurance Like Rebates and Gift Cards?

My daughter got orthodontia last year. We had ortho insurance, which hardly covers the cost, but it does help defray it some. The bill for the ortho is very front-loaded, however, whereas the ortho insurance only pays out 1/3 of its total each year. But as far as I can tell, there is nothing to get the insurer to automatically pay the next year's installment (assuming you are still covered). I had to work pretty hard to get it re-submitted and paid. Which makes me wonder--how many $ or legitimate ortho claims never get paid, because the insured doesn't remember (or even know) that they have to re-submit in years 2 and 3?