"Just take those old records off the shelf, I'll sit and listen to 'em by myself. Today's music ain't got the same soul; I like that old time Rock 'n Roll"
Let's say your first approach was Scrum - and I mean by-the-Scrum-Guide Scrum. It works so well for you that you scoff at Kanban, DevOps, or anything else that violates your 5 ceremony, 3 role, pure and holy Agile approach. Nevermind that you are supposed to be looking for ways to improve every Sprint. Nevermind that the best way to improve team performance is adjustments to the process, not the people. "I'm sorry, you don't use time boxes?" "How do you plan without using User Stories?" "Clearly you don't know what Agile means."
I find it telling that the first line in the Agile Manifesto states that "we are uncovering better ways of developing software by doing it and helping others do it" (AgileManifesto.org, emphasis added). They didn't say that they had uncovered the best way of developing software, they were in the never-ending process of uncovering better ways. They didn't come up with the Manifesto by getting doctorate degrees and jumping into a think tank, they came up with it based on their experiences in doing it and helping others.
I find it highly narcissistic for anyone to have claimed the best way to do anything. Given how long mankind has been on the earth and the fact that nothing has yet been proven beyond improvement, saying that you've "figured it out" means you're either selling something, deluding yourself, or both. Those who really get Agile know that it's about the journey, not the destination. If you keep reliving the glory days of your first Scrum team then you'll never give proper attention to challenging the status quo and innovating the next big idea for delivering software in a better way.
I know, I know, it's hard to give up those first impressions, the glory days, the golden years when everything was perfect and your selective memory hadn't kicked in yet. But you have to if you want long-term success. It's risky business, but somebody's got to do it.