The biggest threat to any long-term Government is voter sentiment that "it's time for a change."
It was Labour's biggest advantage. That advantage has been reduced, if not neutralised, and National, first under John Key and now Bill English, has accomplished a rejuvenation that Helen Clark found difficult in Government.
The Greens are making a feature of their young recruits this election.
Labour has finally managed it in Opposition with Grant Robertson, Jacinda Ardern, Phil Twyford and Chris Hipkins as their new young hopes.
But they are being frustrated by the Government's own.
Adams is the sort of minister who is a nightmare for the Opposition because she rarely makes mistakes and is rarely short of sensible argument.
Her new responsibilities from the reshuffle, the Crown land-building programme she inherited from Nick Smith, cements her place as English's golden girl.
She has charge of the areas where English has a special connection - reforming the state's role in housing, and his flagship social-investment approach to social spending, on top of her large Justice portfolio.
She is hard-wiring social investment into the architecture of Government by taking the social-investment unit out of the Ministry of Social Development and creating a standalone agency with a board comprising the chief executives of Education, Health, Justice and Social Development.
She can be flinty and uncompromising but she is a minister who gets things done.
She has a mission-impossible in the next five months, however, and that is to try to repair the damage to the Government's performance in housing.
She will inherit some big building projects to announce that Smith had under way - Joyce says that will happen before the Budget.
But even with her innate urgency, she will find it hard to overcome the sense that the Government has moved too slowly.
With the reset complete and the new leadership team having found its feet, this third-term Government looks anything but tired.
All of the quartet are unashamedly ambitious - Coleman stood against English and Bridges stood against Paula Bennett for the deputy's job before both withdrew.
But the most interesting subterranean rivalry is between Adams and Bridges. Both were elected in 2008 but while Adams had a head start in Cabinet promotion, they are now ministerial heavyweights with large workloads.
Both are Associate Finance Ministers. Adams specialises in social spending control; Bridges in the business growth agenda.
In the reshuffle, Bridges was handed the Leader of the House role to go with his hefty workload.
It a promotion to a significant job in the running of Government and Parliament that goes unnoticed unless it is done badly.
It involves organising the Government's legislative programme and working closely with support and opposition parties. Bridges' combative tendencies when dealing across the aisle will have to be suppressed.
He takes over from Gerry Brownlee, who earned the trust of Opposition parties and leaves big shoes for Bridges to fill as he moves to Foreign Affairs.
Jonathan Coleman, Minister of Health, had nothing added or taken away in the reshuffle but would almost certainly have become Foreign Minister if Brownlee had not put up his hand.
Of the four young guns, the most politically vulnerable is Nikki Kaye, the new Education Minister, and the only one who is not a potential leader.
Nothing she has done in her previous jobs or even as an Associate Education Minister remotely compares to the demands that the Education portfolio will bring when she starts on Monday.
In interviews this week, Kaye talked about how she wanted to be a "modernising" minister, based on her work getting computers and ultrafast broadband to schools and on upgrading schools' buildings.
But it would be a mistake for Kaye not to continue Hekia Parata's heroic mission to focus the whole education sector on lifting achievement in schools.
It would be a mistake for Kaye not to continue Hekia Parata's heroic mission to focus the whole education sector on lifting achievement in schools.
Despite Parata's terrible start in the portfolio over class sizes, there is no escaping the fact that the most important factor in a child's education is the quality of the teaching.
Parata more or less recovered from the Budget blunder of 2012 (eventually ditched) in which somehow nobody realised that changes to student-teacher ratios would adversely affect 244 schools. Some schools faced losing up to nine staff members, a cut that would have outraged more than just the teacher unions.
Parata subsequently set up a cross-sector forum on raising achievement.
It has been a way to get wide buy-in to the need for constant improvement without an inherent sense of criticism in teachers.
Kaye will have two associates, in Louise Upston and Tim Macindoe, to delegate areas such as computers in schools and buildings, so she can concentrate on the quality of education and lifting achievement.
Given Kaye's recent battle with cancer, Labour is not likely to go for her jugular or demonise her in the short five months she has the job.
The central villain in its sights will be the Budget on May 25.
Joyce and English are both relatively young, having been born in the early 60s, but their extended seniority in National disqualifies them from being considered part of the young club.
It is the mix of experience and promise that the party will be banking on.
