What are the chances of conceiving if you miss your pill just one time?

Registration date
Saturday October 21, 2017
Last seen
October 4, 2019

It's specifically not a question that's directly related to me but looking for some clarity into the matter nonetheless. I have heard that sometimes (though rare) one may end up getting pregnant by just missing one tiny pill. A good friend of mine has happened to conceive recently and she blames it on missing the pill which I much doubt. Curious to know what other thinks of this aspect especially women who've had been on pills and as the human mistakes are inescapable have also missed a pill or two to know what happens then. There are several information online that testify the possibility with of course the emphasis that it's rare. But how rare?