The little All Blacks No9, so instrumental in his team's 51-20 demolition of the Wallabies at Eden Park, has played every minute of the past two tests, a statistic made all the more remarkable by his ability to seemingly attend every breakdown.
At their best, Steve Hansen's men play with a startling speed not many other teams can stay with. The English used all of their experience and a few sly tricks - including pre-lineout conferences - to slow the play down as much as they could when they toured here in June, and the constant rain in Sydney hamstrung a below-par All Blacks during their stalemate at ANZ Stadium.
Perfect, dry conditions in Auckland at the weekend, aligned with a fired-up pack determined to right some perceived wrongs, meant the All Blacks turned up the pace up to almost their optimum level. The Wallabies certainly couldn't handle it and it was a wonder Smith could.
TJ Perenara made an appearance in the 76th minute at Eden Park but he came on for Aaron Cruden, rather than Smith, Beauden Barrett moving from fullback to first-five and the Hurricanes halfback plugging a gap on the wing.
Graham Henry was the among the first international coaches to believe the growing demand on halfbacks meant few were able to last a full test - and he replaced his No9s accordingly - but Smith, who got on the scoreboard at Eden Park when converting Steven Luatua's late try, is proof that that isn't necessarily the case.
Smith also played the entire test against Ireland in Dublin last November, when the All Blacks effectively came back from the dead to win, although that was probably due to the tightness of the test and the fact that waiting on the bench was Perenara, a player who had been named in a match-day test squad for the first time.
Hansen's tactics for the All Blacks' next Rugby Championship assignment against Argentina in Napier a week on Saturday will be interesting. If the All Blacks are lucky enough to avoid injuries to their backline - and they haven't been so far in the Championship - Hansen could elect to give Perenara, who has overtaken Tawera Kerr-Barlow as halfback cover, a longer run to give him experience and save Smith's legs.
Smith was replaced by Perenara in all three tests against England.
The Highlander has consolidated his place in the All Blacks to the point where he is now an integral member of the team. His speed off the mark and passing ability - the quickness of his delivery, as well as the accuracy and, as Hansen has described it, "sympathy", especially when passing to forwards, makes him the spark to the All Blacks' fuse.
The much improved work of the pack allowed him momentum and in doing so made Aaron Cruden's life easier at No10, but Cruden could have been talking about his halfback when he reflected on his team's performance afterwards.
"Throughout the whole squad, everyone was a lot more enthusiastic," Cruden said. "We were on our toes, rather than getting caught on our heels like we did last week. We wanted to take it to Australia... we wanted to control the tempo, control the pace of the game, and it was pretty rewarding to see the tries that we produced."
- By Patrick McKendry of APNZ