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They didn't have to go to the next year in "Aliens of London". They didn't even intend to. The Doctor got his navigation wrong (again!). He'd intended them to arrive 12 hours after they'd left & told Rose that it had been 12 hours. He then discovered he'd got it wrong & it was actually 12 months. By that point, though, it was too late to correct the error because Rose had already interacted with her mother Jackie. That made Rose's absence for a year an "established event" that couldn't be changed without creating a paradox.