This isn't the first time NZ Rugby has given senior players time off - the most obvious examples were former All Blacks captain Richie McCaw and first-five Dan Carter, who both credited their sabbaticals for extending their careers as far as the 2015 World Cup.
The only other case where rugby has given a star player time off was when Australia allowed veteran flanker David Pocock a year off to travel Africa and carry out charity work.
"Offering their leading players the option of a sabbatical was originally viewed as a ploy by the New Zealand Rugby Union to simply keep their top talent happy with the option of a well-paid stint overseas, before returning to the All Blacks, which is certainly the route Dan Carter went back in 2009, when he joined Perpignan," says Coles.
"As rugby has grown ever more physical, the purpose of the concept has changed entirely. A sabbatical now represents the chance for a mental and physical reset from a brutal schedule, as opposed to a quick payday.
"When pinpointing why the All Blacks still sit ahead of the rest of the world, even with England closing, the sabbatical is a trump card."
In Smith's absence, coach Steve Hansen will likely use the opportunity to develop his depth at fullback, namely Jordie Barrett and possibly Damian McKenzie, both of whom promise to be key players in the programme moving forward.
That continual development is one of the reasons the All Blacks never have to rebuild.
NZ Rugby hasn't always got its player management formula right. Remember the "rest and rotation" policy of 2007, when players were pulled from Super Rugby for a reconditioning programme?
But the sabbatical concept is more player-driven - they can take it when and if they feel they need it - and currently only available to those who have given long service.
"If the gap really is closing on the field, New Zealand still hold a major advantage off it," says Coles.