Leadership changes are sometimes described as bruising affairs. I always thought that was putting it a bit lightly. Bones shattered and cracked would be closer to reality. Friendships are destroyed. Lifetime enmities are forged. Colleagues who have fought side by side for years will never talk again – and that’s just the staff I’m talking about.

The two words “transaction costs” have been everywhere this past fortnight to explain some of Labor’s reluctance to change its leader. It’s a useful phrase, covering a range of evils, but the bloodless words, perfect for our sterile, market-driven times, do nothing to evoke the roiling emotions involved. We are talking about spiteful attacks by bitter, vanquished leaders, instability caused by damaged egos and voter disgust at a party’s self-obsession.

None of these is inevitable. Nor are they an argument for never changing leaders. Leadership change, at the right time, can be reinvigorating, even essential. But they are important in understanding why the two major parties, both of which have recently lived through such schisms in government, are increasingly nervous when it comes to calling time on leaders. Politicians are pragmatic, but they have the same human qualms – or most of them – as the rest of us.

The Super Saturday byelections delivered a convincing victory for Labor. The government can offer a million excuses to suggest the results were not a verdict on the Prime Minister. Perhaps the decisive factor was Labor’s huge ad buy, or the letter that went out from Catholic schools, or the medal controversy around its Queensland candidate. But these aren’t excuses, they’re reasons, and they will still be there at the federal election. Labor’s campaign tactics, policy that makes the government vulnerable, the Coalition’s failure to preselect well, all of these are reasons for fear, not comfort.

So the results are good for the opposition. Do they prove that Bill Shorten is the best person to lead Labor? Of course they don’t. In politics there is no such thing as proof. The byelections have been run and won, and we will never know how another Labor leader might have fared in the same conditions. Obviously, Anthony Albanese has the same advantages over Shorten – authenticity, a certain forcefulness - he had before the poll. Saturday won’t have changed anyone’s mind on that.