I canvasssed for the first 2 years here in Ireland, as I found that the retention rate was quite low. This I put down to the fact that we were in the middle of the recession, so quite a few proved to be one-offs. Added to that was that I was a stranger in town.
Since then I have picked up enough good, regular customers from walkups, but, mostly by way of word of mouth recommendations.
In answer to the original question, all my regular customers are all equally valuable to me irrespective of how I got them.
John