Good information Sparky, but I don't think the song was about him (Johnny Cash)... or was it? 
It's just one of those weird questions that I have many of. 
Like...how long should I hold a door open for a person behind me?
At what distance must they be before I say to myself...too far away, I'll just let the door close.
 But if it's a nice looking female, should I hold the door open longer for her, than say, for someone... like Chas 
 Larry ( no not Larry David) 
