Shaking the dust off

It seems that whenever we venture into Mark 6:10-12 or similar verses it leads to a discussion of how long do you try to teach someone. I have come to the conclusion that this is the wrong question to ask in our everyday lives. The context is an evangelistic trip, that had a beginning and end. If they were going to specific towns then they had a limited time to talk to people and it would be better to talk to receptive people than non-receptive.
Today the vast majority of us are not on an evangelistic trip, but living normal lives of going to work, coming home, and maybe raising a family all from the same location. Consequently we meet mostly the same people everyday. If we look at sharing the love of God as relational, there isn't a time limit, as the apostles had. A relational approach is not asking the same person everyday to study the Bible. It is getting to know people and living our life so that others know we are believers. We help people know God through our friendship and talk about God at times when it can help. This is the opposite of just making friends to convert someone and then dropping them if they don't respond in our time frame.
Not everyone is going to respond to our friendship, and there will probably be people we just can't be friends with. But this does make the question of "how long do I to try to teach someone," irrelevant. After thinking this through I reminded myself that there are no absolutes in personal relationships, so remember that as you think on this.