I think one thing that people are overlooking is that a let's say 30 prescription can usually be filled several days early so that you don't run out. Over time this let's you build up a surplus. By doing this for PreGabalin for over a year, I was able to get about a month or more ahead. I didn't need my 3 month refill at the end of this year, but since my deductible was satisfied my OOP was about a third of normal. Some folks who might accumulate a surplus of more potent drugs in this manner might be tempted to sell off the surplus so it could be for that reason that they aren't fully filling the prescriptions.