Foster said one of the results of the nature of the 2021 season and the long tour especially, compared to the Covid-19 interrupted 2020, had been the development of more consistency in preparation and the development of good habits in the side.
Behind every aspect of modern Test, rugby was growth in the World Cup cycle, and Foster said with refinements in their game over the next two years that should prepare the All Blacks for the 2023 Rugby World Cup.
Every game was a step along the way, and a confident Ireland side was the next challenge.
"We're as ready as we can be for this game, and we're not lacking for any motivation," he said.
"These are the big stages that we seek and, as a team, I think we are still a developing team.
"We're still growing in what we want to do and these are the games that you put a marker down and you get the answers to where you are at in some aspects. We can't wait to give it everything and see what happens," he said.
There would be unexpected issues to deal with in the game, and that would be something new for players who had not had experience in the northern hemisphere to deal with, he said.
In their last outing against Japan, Ireland was motivated with great intention to play and looked comfortable moving the ball more than had been the case in recent years.
That, combined with their growth in the last Six Nations, showed they were well prepared. That would result in a great contest on Saturday, he said.
Ireland first five-eighths and captain Johnny Sexton looked sharp against Japan and was a quality operator, and while he was 36, he didn't look like a player with an old attitude.
"I don't think age is anything, it's about the athlete and how old he feels. He's very competitive and wants to get engaged so I guess that's the quality they're still loving," he said.
Foster said his midfield choice of Anton Lienert-Brown at second five-eighths and Rieko Ioane at centre stemmed from how the All Blacks finished the Welsh game. They showed plenty of energy, and their attacking mindset changed the team's dynamics a little. When combined with Sevu Reece on the wing, it was the way the selectors felt they could best start the game with Ireland.
He was also confident that Lienert-Brown's in-game transfers to second five-eighths would see him ready for the role against Ireland. He often shifted during games and had practised throughout the tour in the position.
Ioane was playing well at both wing and centre. His ability to handle the change, often in games, was because he prepared to do both.
"There's not too many players who can demand a starting position in two positions and I think he's shown a great maturity, the way he has handled that, and it has given us the opportunity to use him in different roles in different phases of the game," he said.
The intention was to get the ball in his hands early against Ireland to get him running.
"I think he has had a great tour and has grown quickly as a centre. He's still got some work to do as everyone has but I'm delighted with his progress," he said.
Selecting Ethan Blackadder on the blindside flank was using the skillsets best suited for the game.
"It's a very physical and close-quarter game up here, and I think that suits him. He's got a lot of energy, he's very uncompromising, and he's adding the skill part to his game all the time.
"We know it's going to be a battle up front, the Irish pack is a tough pack, but the breakdown is important and the quality of your ball carrying and defence is important and, in a couple of those areas, Ethan has made quite an impact for us," he said.
Beauden Barrett suited their plans for early in the game. That was why he would start at first five-eighths. Foster said he had no qualms with either Barrett or Richie Mo'unga, who were both quality players.