In Harry Potter and the Cursed Child, Scorpius and Albus go back in time to change the events during the Triwizard Tournament.
From their own timeline (1), they visit the first task, and succeed in creating a new timeline (2) that's slightly different. Then, they visit the second task, creating a very different timeline (3) in which Voldemort wins the war.
Scorpius then finds Snape, Hermione and Ron, and the group set about reverting the changes, going back to timeline (1). At this point, the obvious thing would be to go to the second task, reverting to timeline (2), and then back to timeline (1). Instead, they start out by visiting the first task, creating yet another timeline (4), which is very similar to (3).
Why would they do that?
Why create a fourth timeline, which may be very different to any of the others? For all they know, it might be impossible to return to the second task from timeline (4). Going back to (2), besides being the natural thing to do, should be much safer. What's the rationale here?