How time travel works in the DC universe ?

[Lorendiac]

There was a thing during the New52 Legion of Superheroes and Legion Lost that something was blocking time-travel, but I don't remember this ever getting resolved and since then there's been a few of time-travel stories. So I guess they're just going to ignore that ever happened.

This just reminds me of a precedent from about a quarter-century earlier, right after "Crisis on Infinite Earths!"

In the years following the transition to Post-COIE continuity, I've heard that the editorial policy was supposed to be something along these lines: "Time travel is still possible in the modern DCU, but it's rare. Much less common than it was in the old days, when Superboy/Superman could just fly really fast and make it all the way to the 30th Century -- or any other era he pleased -- by sheer willpower, and then return to the 'present era' at the drop of a hat. To make this stick, we're enacting a rule that the typical person can only travel through time three times in his or her entire life. If he or she tries to press it beyond that, the strain will tear him or her apart."

I think that lasted, more or less, for some years . . . but I have the distinct impression that this policy was already pretty well abandoned by the time of "Zero Hour" in 1994. Too many writers and editors had too many ideas for other "time travel" stories they wanted to do, and they were willing to just ignore any arbitrary restrictions such as "your superhero has already used up his quota."