With all the six bands now reunited, it was time to check the proof of the pudding, with the first rehearsals before the Big Reunion concert.
Despite all six bands sharing equal billing, everyone knew there was really only one star in town, and Her Royal Reality Kerry duly accepted her dues, turning up latest and loudest.
But there's nothing more levelling than dance and voice rehearsals, particularly for people who've been too distracted for a decade or so to attend a Pilates class or sing in the shower, and the smiles gradually faded as the bands stretched for the same old magic.
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As 5ive got moving, Abs' hat stayed on throughout, but one of them was having an existential struggle with between old Sean and new Sean - "they nearly met," he explained helpfully.
Meanwhile, Kerry was in the studio with the girls, hamming it up like a teenager trying to imitate her favourite band, which she just happened to be in. Except, unlike a teenage fan, she didn't know the routines. Or the words. "I left, and then they got to number one, and I wasn't bitter," she pointed out. Something tells me personality alone will see her through.
The B*witched girls were still pretending they were all equally proficient as front women while Edele sulked silently. And the Honeyz oozed their way through their first song. "This time at least we know we can all sing," they said. "I'm missing something, maybe some attitude," the vocal coach said. Are we learning that musical talent and the oomph factor may be mutually exclusive?
And 5ive's challenges continued with the ongoing search for Jay's replacement. Come on ITV2, if Blue can join halfway through, surely the elusive frontman can be persuaded to return, and give this show the punchline it deserves, if only to see the look on Sean's face.
WATCH: The 5ive boys tell 4Music that they wouldn't take Jay back now, even if he wanted to return!
First day of training was celebrated by a night on the tiles, which was basically a reality show, exactly half-way between 'Made in Chelsea' and 'TOWIE'. Chelsea, but less champagne, TOWIE but less orange.
Best fun was the bands sitting together to watch their old selves - Kerry ribbing 911's Lee with her "you hadn't hit puberty there" - an occasion summed up perfectly by the Honeyz as "surreal, but hilarious".
And the final group showcase proved this week's two life lessons... that there's plenty of fun to be had of a reunion, and that, stripped of the hype, the glitter, the screaming fans, none of these bands have much on an enthusiastic bunch of teens on a school stage. One Direction need waste no sleep just yet. Or not until Blue turn up next week, anyway.