I'm just like my Dad in finding it extremely difficult just to wait on something. I don't mean in the sense of impatience, exactly (there's that, too, but it's another issue!): it's more of an intolerance of uncertainty. I really admire those who, in the words of a former classmate of mine who was a physicist, "have learned to live in peace with incompleteness."
Dad has by far the harder part right now, not knowing whether or not this time of suffering represents the immediate preparation for the "completion" of his course on earth. And we are bearing that with him.
At least the souls in Purgatory have some sense of certainty about their situation! They know, and are delighted to know, that Heaven--God!--is truly and completely theirs. They just don't know when they will be truly and entirely God's, free from all the self-centeredness that dominates us, thanks to sin.
If, as St. Catherine of Siena said, "all the way to Heaven is Heaven," then surely all the way to Purgatory is also Purgatory!