The length of the Injustice story can vary depending on how you measure it. If you consider the comic series, it's quite extensive. But if you're talking about the video game or animated adaptations, it's shorter and more condensed.
I'm not exactly sure. It might vary depending on different editions and releases. You might want to check with comic bookstores or online comic platforms for the most accurate count.
Injustice 2's story is quite substantial. It has multiple chapters and missions that can take several hours to fully experience, especially if you take your time to soak in the details and side quests.