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Robertson was overlooked by New Zealand rugby's selection panel in favour of Ian Foster as Steve Hansen's replacement as the next All Blacks head coach, with the appointment announced late last year.
Speaking to Radio Sport's Jason Pine, Robertson opened up on the panel's decision and what he learned from the process.
"The Christmas break came at the perfect time for me just to reconsider a few things. You go for the job, you're confident; I'm a natural competitor so I saw myself in the role and doing a great job," Robertson said.
"There was an initial disappointment, and then you start to find out the reasons why or what could I have done differently.
"You start to reflect on all that and what it means for me as a coach and my future; I honestly felt like I would have made a difference.
"Once I had time to reflect on what it means for me, I sort of stepped back and thought OK, it's going to be another time. I have a little bit of a plan of how I can get better, that's one thing I've got to do as a coach so the next time it comes around I'm even better than I am now.
"What does it mean for me? It's to make sure I trust myself and have good belief, and hopefully the next panel is brave enough."
When asked if looking at career opportunities overseas was an option in his plan to improve, Robertson said there was the potential for him to look offshore but for now he was focused on his role with the Crusaders.
Last month Sir Graham Henry, who was on the panel of five that recommended the coaching candidate to New Zealand Rugby, said it's a matter of when - not if - Robertson is given the top job.
"I think he's got the passion to coach the All Blacks and that's what he really wants to do and I think it's in his psyche," Henry said.
"I think he will be the All Black coach, it's just a matter of time. He's 45, isn't he? He's just a baby as far as coaches are concerned, very talented, very enthusiastic ...he's just got to be a bit patient."
Robertson will return to his post as the defending champions' head coach looking to lead the team to a fourth straight Super Rugby title in as many seasons at the helm.
As is the case with many of the Super Rugby sides, the 2020 season sees the Crusaders roll out a new-look side, with veterans such as Kieran Read and Matt Todd stepping away after the 2019 Rugby World Cup.
"It wasn't my time (for the All Blacks role). I'll get another crack at it and now it's my chance to bring all that energy into the Crusaders. It's a different challenge, and that's what excites me. I'm fresh and ready to go."