Why is Spy x Family not in Weekly Shonen Jump?

Lin's account, from The Making of a Jump Manga, is the documented chain: he was transferred from the Jump Square editorial department to the Jump+ editorial department, Endo told him any department was fine and they would work together again, and the two slowly drew up a plan for a work that would suit Jump Plus. The platform came first; the work was designed for it. There is no on-record account of Weekly Shonen Jump considering and rejecting the series, and this page does not print one. The print magazine did run a preview chapter in its 2019 issue 17, as advertising for the digital launch, which tells the same story: digital first, by design.

Spy x Family launched on Shonen Jump+ on March 25, 2019, biweekly on Mondays, with a free simultaneous English release on MANGA Plus the same day. The run rewrote the platform's record book: Volume 6 in December 2020 was the first original Jump+ manga to receive a first print run over one million copies, and by June 2021 it was the first original Jump+ series to pass ten million copies in circulation. New chapters were drawing over 1.2 million views on release. One inference needs its label: the biweekly pace is often credited to Endo's post-slump health, but neither Endo nor Lin states that reason on record, and biweekly is a normal Jump+ cadence. It is printed here as inference, not as their stated reason.