The one successful midstream change anywhere that I can recall was Hawke to Keating in Australia, which might be why today's Australian Labor Government imagined it could safely replace Kevin Rudd with Julia Gillard three years ago.
What a disaster that turned out to be, and what a sorry denouement we watched on Wednesday night.
Once the result was known, we watched an empty corridor waiting for victor and vanquished to appear. Neither was in a hurry to address the nation. The whip who delivered the ballot figures said the nation was probably watching Origin 2. Clearly he hoped so.
Sometimes it is better to live with a mistake than try to correct it. One needless leadership change betrays a government in disarray, two can only confirm it.
For us, the sequence recalls the Lange Government's second term, though there were differences. Lange was clearly the architect of his own demise and it came as a relief to the public. He didn't haunt his successor as Rudd has, and when Sir Geoffrey Palmer's caucus came to much the same decision as Gillard's did, Palmer went without complaint.
Helen Clark, who handed the poisoned chalice to Mike Moore two months before the 1990 election, could have been New Zealand's first female prime minister at that point. She didn't want the job in those circumstances for the same reason that I doubt Rudd wanted it on Wednesday.
Neither he nor Gillard were particularly impressive when eventually they spoke. Gillard was dignified but mechanical, Rudd was nauseating.
He had the gall to condemn whispering campaigns and said they must now stop. Worse, he seemed genuinely unaware of the irony. He also said he was worried that young people were disillusioned so he threw in some youth lingo.
You could see how his colleagues came to loathe him and why so many of the Cabinet were quitting.
Nevertheless, they did wrong. Dumping a prime minister who has won an election is a prerogative the public prefers to reserve for itself at the next one.
Watching the Australian debacle, it was hard not to feel an immense satisfaction with our own politics these days. Helen Clark survived three terms without a whisper of dissension in her party and John Key looks quite likely to do the same.
The country has been more content since the millennium than at any time I can remember. It might have been like this in the 1950s and well into the 1960s before the economy entered shoals that got much worse in the 1970s.
Then came the reforms. We have come a long way and it was rocky. We've earned the stability of the economy and our politics now.
Australia went into the same rapids a little ahead of us, took a slower and less radical course. But they had a bigger boat and more stable leadership in those years. Perhaps that explains their politics now.
Much of the criticism of Gillard has seemed out of all proportion to her errors. I got a taste of it in response to a column that admired the way she engaged this country when she visited in the aftermath of the Christchurch earthquake. It was the sort of vitriol you delete at a glance.
One unwelcome correspondent supplied some of the cruel and obscene cartoons that were circulating at the time and I can see why she believed her gender contributed to her downfall. But I doubt that it did significantly.
Australia's first female prime minister, like New Zealand's, had the misfortune to come to office on a vote of her caucus, not the country. Gillard went one better than Jenny Shipley by narrowly surviving the next election, but she was taking the party over a cliff in September.
She hopes she has cleared a path for Australia's next woman prime minister, and the next.
She hasn't, the next one will be fine as long as she comes in on a popular vote, as the next in New Zealand did.
