Since taking over as coach in 2020, Rennie has seen 20 players make Test debuts and, so far as he is concerned, that is enough for him to be confident Australian will have the required depth as they set their sights on winning the World Cup for the first time since 1999.
Knowing he has a maximum of 15 Tests this year - the programme is still to be confirmed - Rennie believed the balance between youth and experience is the key for the side's hopes.
"I'd expect us to have a more settled look around the squad because we've got a lot of knowledge, and we've got a lot of confidence in the guys we're using," he told rugby.com.au.
But it was still up to the players to perform and build on what experience they already had. However, the selection door was not closed for any bolters who emerged.
"We're certainly not going to close the door on anyone jumping out of the pack. The door's always open. If someone emerges from left field, they'll be rewarded," he said.
Experience, especially in the white-hot atmosphere of the finals stages of a World Cup, was vital. Winning squads have been older with successive tournaments.
Rennie said those older players still had to perform to be selected.
"Just because you've been around a long time doesn't guarantee you being part of a World Cup," he said.
"What we've been doing over the last couple of years is picking some young men who, hopefully, by the time they go to a World Cup, have got 40 Test caps under them – or maybe more.
"We learnt a lot last year. We had a tough international season, and we've got another one which is awesome," he said.
Rennie was keeping an eye on utility back Kurtley Beale. He may return to Super Rugby Pacific this year when his French stint is complete.
Beale was one of several experienced Wallabies selected for Australia's November tour last year.
Beale impressed Rennie, and with 95 Tests caps, he was an ideal asset to provide some of the core experience the team management wanted.
"He looked sharp against Wales, and his point of difference has often been his speed and footwork and making sure that's at the top. That's probably the challenge for him.
"If he's coming home, that would be great from our perspective because we'll have a lot more influence from a Super Rugby point of view compared to if he was playing in France," he said.