In a game scenario, the attacking team will have two or three threat runners attacking the line and the playmaker, often the No10, will sum up the shape of the defence, note where the gap or hole is, and pass him the ball.
It's important for the non-receiving players not to adjust their line but to attack the outside shoulder of the defender, keeping himself between the ball and the tackler.
It is in this last instance that the attacking runners are often accused of obstruction.
Q. What do rate as your greatest All Black try? My family say Jonah Lomu steamrollering England fullback Mike Catt at the 1995 World Cup. I reckon Sir JK outrunning 13 out of 15 Italians at the 87 World Cup to go 70-plus metres to score - legend.
Phillip Millar, Lake Taupo
Phillip you got me thinking how lucky I have been to see, and sometimes even be a part of, some wonderful All Black tries.
To pinpoint the greatest is so hard, but I will give you a list to enjoy.
• Peter Jones's try in the fourth test against South Africa at Eden Park in 1956 to wrap up the series.
• Another Northlander, Joe Morgan scoring the only try of the match in the first test win in Bloemfontain in 1976. This was my first memory of getting up with the family to watch the All Blacks in the early hours and being able to watch two Northlanders, Joe and Sid Going play was special.
• Hika Reid's length of the field try v Australia in 1980. Hika started and finished it after Bruce Robertson made a great break.
• In my era, John Gallagher doubling around a flying Terry Wright at Lansdowne Road will stick in the memory.
• Frank Bunce scoring under the posts v Australia in 1992, after the ball went through nine pairs of hands.
• Josh Kronfeld showing the width and pace we played at during the 1995 RWC with his try against Ireland.
• Jeff Wilson v Australia in 1996. A near-complete performance in atrocious conditions at Athletic Park.
• Jeff again in Pretoria. A special day in NZ rugby.
• Christian Cullen ... where do I start? 1997 against Australia in Dunedin, turning George Gregan inside out, and then finishing off a slick backs' move involving two wrap-arounds in Sydney that same year.
• More recently, Israel Dagg silencing 94,000 South Africans at Soccer City to win it for the All Blacks in 2010 and Tony Woodcock's effort against France in the 2011 RWC final.
I know I have missed out so many more and you will have your own favourites that you can recall and enjoy.