That is an interesting question to ask yourself. In some cases, such as physical violence, the answer is clear and direct. You should not be patient at all. If you date someone and they get physically violent, you need to leave at a run and never return. Will they recover or change? Maybe, but never with you if they've been violent with you.
But in other cases, 99% of what we encounter in our lives, the answer is that if you are asking the question then you haven't been.
Too often we have been part of whatever the problem is, and not outside, nourishing and helping, anywhere near long enough. One thing I've gotten from Leadership and Self Deception: Getting Out of the Box is that a belief I've had, that you can make a difference if you just take the time it takes, is true -- and that many, many times, we have not taken the right steps, in the right way for anywhere near enough time.
On thing grief has done for me is teach me that things take time. It has also taught me that so many things I thought or think I am doing are not the same the way I see them as others see them. I see that so often with others that I am certain that it must apply to me as well, and that just like they do not see it in themselves, I can't see it in myself.
The approach of patient, caring love seems like the only answer.