Whether by cunning or incompetence, she is taking Brexit to the wire - which her admirers and critics say might have been her plan all along.
According to European leaders, everything should have been settled by now. But nothing is settled at all. And unless there is another delay - a possibility - Britain is scheduled to leave the EU on March 29.
After spending two years in Brussels talking, a final withdrawal agreement was promised by October, then November, then December. Now January.
And the Prime Minister is offering British MPs, especially those in her own Conservative Party, the starkest of choices: Her deal or no deal.
Over the holidays, May wants her fellow Tories to have a good, long think about the cost of leaving the European Union with no deal, a scary scenario that envisions economic chaos and cancelled European holidays.
May's Cabinet yesterday activated a multi-billion-dollar emergency plan to prepare for no deal, including sending letters to 140,000 British firms updating them on what they should do now, beyond pray.
Defence Secretary Gavin Williamson also announced the British army will place 3500 troops, including infantry units, on standby, "in order to support any government department on any contingencies they may need."
What might British soldiers do in a Brexit emergency? Free up police busy putting down civil unrest; patrol the English Channel to stop goods smugglers and human traffickers; airlift vital medical supplies; and use their cargo ships to ferry food and fuel.
Is this prudent planning - or something else? Sir Vince Cable, leader of the Liberal Democrat Party and an arch-opponent to Brexit, described the announcements and their timing as "psychological warfare".
The Labour leader agreed. "There is still no majority for her shoddy deal in this house. It isn't stoical, it's cynical," Corbyn said. He accused May of ramping up contingency plans for a no-deal Brexit as a way to drive through her deal.
"Stop dithering and put it to a vote!" he bellowed.
Not to be outdone, May accused Corbyn of not having no realistic Brexit plan and of stalling himself.
"It's a bit rich him standing here talking about dithering," May responded. "Let's see what the Labour Party did this week. They said they would call a vote of no confidence, then they said they wouldn't, then he said he would, then it wasn't effective."
When May was finished, Corbyn appeared to mouth the words "stupid woman". His party later claimed that he had said "stupid people".
Many British hosts of Christmas parties have tried to ban guests from arguing about Brexit - but it is hopeless.
At his annual gathering for diplomats and journalists, Foreign Secretary Jeremy Hunt pointed out that there were bigger problems in the world than Brexit. He mentioned Yemen.
At the Christmas fete at the Irish Embassy in London, a journalist with the Daily Mail had to be escorted from the room after shouting "Brexit!" during the ambassador's speech. This made the newspapers.
Upon news of further delay, Carolyn Fairbairn, the director-general of Confederation of British Industry, which represents 190,000 businesses, warned her members were absolutely desperate for clarity.
"Investment plans have been paused for two and a half years," she said. "Unless a deal is agreed quickly, the country risks sliding towards a national crisis."
In the Commons debate over Brexit on Tuesday, Justine Greening, a Conservative pro-European former Cabinet minister, said: "We have spent two and a half years going round in circles and we cannot simply go nowhere, we have to now take some decisions about going somewhere."
Greening said, "People simply won't understand why this place is packing up and having a two week holiday when we face the biggest constitutional crisis that this country has had in decades. It is simply wrong. The Government has to recognise this."
May said she will be busy over the holidays seeking "assurances" from the European leaders on her Brexit deal. Well, yes, maybe. The Europeans have said no meetings are scheduled.
Diplomats in Brussels familiar with the negotiations said that May's decision to scrap the December date for her parliamentary vote, just days before a summit of EU leaders, was a serious miscalculation if her aim was to extract concessions - or even symbolic reassurances - from Europe.
Leaders of Germany, France and the Netherlands have made clear there won't be any substantial changes to the agreement on the table.
By delaying, the thinking goes, Downing Street and the parliamentary whips will have a little more time to cajole, frighten and squeeze MPs who don't like May's deal. They hope that once members are away from the fractious, poisonous, febrile atmosphere of Westminster, in the bosom of family and friends and frustrated constituents, that upon reflection and a couple of stiff drinks over the holidays, they might see May's Brexit in a more favourable light.
Yet it is May's fellow Tories who appear as frustrated as anyone with the endless delays. Anna Soubry, a Conservative MP, accused bluntly May of "blackmail".
Sam Gyimah, a Tory MP who resigned from May's Cabinet over Brexit, charged that Downing Street had stopped trying to sell May's deal as a winner, and are instead trying to "discredit every plausible alternative as they run down the clock. This is not in the national interest".
It's hard to see how May will get her deal through Parliament. And yet. It's still the only deal that Brussels has agreed to, and the only one just a parliamentary vote away from getting a green light.
All other possible alternatives - and there are many being floated, including a second Brexit referendum - face even higher hurdles along with the ticking clock.
Over the coming weeks, May's deal "will be, I'm sure, like a piñata," said Rob Ford, a politics professor at the University of Manchester. "It will be repeatedly beaten with sticks from all sides and called dead, over and over again, by all sorts of people who want to call it dead, but that doesn't make it dead."
Why? Because it averts no deal, Ford said.
Running down the clock was the obvious strategy given the many factions and conflicting demands in Parliament.
"But I don't think anyone looking at this is kidded into thinking that there was a strategic genius behind this all along, even if it passes," said Anand Menon, a professor of European Politics at King's College London.
Menon said May was struggling to sell her deal now in part because she is not a great communicator, and she never sufficiently prepared MPs or the country for the costly trade-offs of any deal with the EU.
"So now, all of a sudden, people go, 'hang on, you promised us frictionless trade' and she's 'oh yeah, that was impossible,' and people say, 'you said no deal was better than a bad deal,' and she's 'oh yeah, I was kidding.' So it's only now that the those trade offs are being spelled in out in a coherent way and even now she's not doing it particularly clearly."