Stuart Lancaster ranks temperament and skill alongside experience when it comes to making the big calls.
He has learned through his experiences that age is not a barrier as long as the boy plays like a man.
"I have to go back to my time with England," he started.
"I think I gave the first cap to, probably, 40 odd players.
"Time and time again, it was Anthony Watson or Jack Nowell, Jonathan Joseph, Owen Farrell, George Ford, the list went on with the young players I gave opportunities to.
"If they show they have the temperament and the skill set and the ability to play at the highest level, then I don't believe age should be a barrier."
The senior coach needed no prompting to move specifically on to the special case of Jordan Larmour.
"Take Jordan as an example, it's not just that he has been thrust into the senior team," issued the Cumbrian.
"He's been training with us non-stop now, certainly since the time I've been here.
"The things we've seen him do in games, I've seen him do for the last six months."
In truth, Lancaster and head coach Leo Cullen look like they have made subtle changes from coming up short last season.
There does seem to be even more movement, in terms of going with the young guns like Larmour, Andrew Porter, James Ryan, Josh Murphy and Max Deegan.
"What people often don't appreciate in player development is that it is getting the players to the senior squad that is important," he said.
Once anyone gets there, they have to thrive, not just survive.
"The real difference is that when those players are in the senior squad that they are given genuine opportunities to participate in training, not just hold bags or to be token opposition."
For all that, here is a balance to be struck between the men of today and tomorrow on the big days.
For all of Leinster's slow-cooking of young talent, the spine of experience has to be in place.
"That's a balance, isn't it?" responds Lancaster.
"The trick for us is to pick the right players for the right game and also use the strength of our squad to our advantage."
This is where Leinster are inclined to make more changes for Montpellier than they did for the second of the back-to-back matches against Exeter.
"There will be changes between game one and game two which, I think will freshen our team up."
Then, Lancaster broke with the conventional one-game-at-a-time mantra to reveal the longer-term thinking of the coaches.
"It is reasonable to suggest that we would plan that far ahead," he said.
"It is not just the next two games because you know, after that, there will be a significant number of players going away with Ireland.
"We should e thinking ahead to who we are going to play in the next rounds of the PRO14. It's always about being one step ahead."