After the passing of its Paid Parental Leave and Healthy Homes Guarantee bills, both of which were existing private member's bills, Labour has relied on bills of the former National Government to fill up December debating time - bills which are acceptable to Government parties and which were carried over to the new Parliament.
National's shadow leader of the House, Simon Bridges, and senior Whip, Jami-Lee Ross, spotted an opportunity.
National kept its contributions to debate to such a minimum that legislation was whizzing through the House at an alarming rate – too fast for Labour's buffer of comfort.
No Government can afford to be seen to run out of business, for any reason. The Government was not in danger of running out of business on Wednesday, but the speed-debating gave it less room for error next year and it needed to apply the brakes.
The result was that hellishly busy Labour cabinet ministers were instructed by their party to drop what they were doing on and get down to the debating chamber to help drag out debates on issues quite unrelated to their portfolios.
That is unheard of. The filibuster is one of the few weapons of protest for an opposition, not a Government that supports the bill it is trying to delay.
It was forced into it by the Opposition and as a tactic to disrupt the Government, it worked well.
It boosted National's morale and sapped Labour's but only temporarily.
Other choreographed events this week ensured that the Government did not lose control of the political agenda: Chris Hipkins' release of details of the fees-free policy, the release of the Havelock North water quality report by David Parker and David Clark, and the release of the Government's response to soaring petrol prices by Megan Woods.
Labour's House programme is being run by Hipkins, the Leader of the House. He appears to have an impossibly high workload - overseeing the fees-free policy to be delivered on January 1, overseeing Ministerial Services Minister at a time when the every minister is setting up his or her offices, as well as the legislative agenda to be delivered within 100 days of taking office.
While Hipkins is in no danger of losing his Leader of the House job, he has had a less-than-glorious start when combined with the horse-trading debacle over the appointment of Speaker Trevor Mallard.
Mallard himself has had a controversial start with National, no more so than this week.
That matters because the House is a more important platform for the Opposition than for the Government, which can muster attention almost any time, anywhere.
Mallard has the potential to be an excellent Speaker and to allow National to be more effective in the House.
He is the best prepared for the job than any of his predecessors. He also had three years to think about what sort of House he wanted to run, especially at question time, but that means he has strong views.
The trouble is that he wants to change patterns of behaviour in MPs rather more quickly than they are capable of changing.
He wants questions asked in silence, a better quality of question and a better quality of answer by ministers - essentially a better demonstration of the Opposition holding the Government to account.
He wants the House to be free-flowing and for himself to be a less interventionist. But he is trialling a deeply unpopular system whereby he continually inserts himself into the play by dispensing instant penalties and rewards, removing or adding supplementary questions to parties.
He demands respect from MPs because of his position but this week was repeatedly dismissive of National's shadow leader of the House, Simon Bridges, by anticipating what he was going to say and not allowing him to say it.
Previous Speakers, even at the end of their patience, have almost always accepted contributions from MPs holding such senior positions rather than humiliating them, as Mallard did this week.
Bridges also has to take more care in the execution of his role. As shadow leader of the House, he is playing a highly active leadership role in the new Parliament and he wears his ambition on his sleeve.
But it is not going to help him or his party if his default position is to engage Mallard as a combatant or to repeatedly suggest he is biased.
Mallard may have made the odd dubious call which has helped the Government but he has the ability to self-assess and self-corrected. He wants to be a good Speaker and even Barnes came right in the end.