It knocks more than once but unfortunately some of us are hard of hearing and miss the early one.
There are certainly opportunities which only knock once. That person you met once and thought about afterwards but didn't get a contact. Similar ones may come up but only rarely do we meet most of the exact same people again.
Opportunities come by us all every day. Most of them are tiny seedlings. What really counts is how well we feed them and you will find that most people who got somewhere did so by nurturing their idea even when it meant sacrificing other things.
That to me is more the important factor in success than the number of opportunities we attract in our lives.



