Red Bull clinched its sixth constructors' title with six races to spare in Japan, which is another entry for the Milton Keynes squad into the series' record book that it has been steadily rewriting this year.
Team principal Horner conceded that losing its streak of consecutive race wins in Singapore was inevitable.
And while the carrot of an invincible season is no longer dangling in front of his team, Horner says it must continue "pushing the boundaries" as its current success will be hard to replicate.
"I think a repeated season like this is, you know, it's a golden moment for the team," he said.
"To do better than we're doing I think it's impossible. So, I think we're riding a wave and of course we want to try and ride that wave as long as we can.
"But Formula 1 is a fast-moving business. You see how quickly teams move up, move down and Singapore if nothing else demonstrates that there can be zero complacency, that we have to keep pushing the boundaries."
Horner also paid tribute to the crew members that produced such a dominant RB19, which displayed almost no weaknesses and in the hands of series dominator Max Verstappen sat at the top of the pile across all speed ranges.
"Last year was a very strong year for us," he added.
"But to have kept that momentum, rolling with the challenges that we've had is testimony to all the men and women in the team that have worked tirelessly to produce a car as competitive as we've had, that the drivers and particularly Max has been able to make such good use of."
Horner admits Red Bull's results were helped by rival teams being inconsistent as the status of second-fastest team constantly appears to change hands.
Instead, Red Bull remained a consistent factor despite its success handicap from F1's aerodynamic testing restrictions and its penalty for exceeding the 2021 budget cap, which prompted the outfit to be more efficient in its development.
"The field has been moving around behind us. One week it's McLaren, next week it's Ferrari, the next week it's Mercedes," he added.
"We've been 90% consistent at the front of the field and we've been fairly limited in the amount of development that we've done on the car.
"The regulations are stable, so we have the same gearbox on the car, we have the same chassis largely as last year so an awful lot of is carried over.
"The team has done a great job in efficiently developing the car and reducing the weight, and to maintain this kind of performance across the variance of circuits that we've had."
