How long can a titan shifter stay in a titan form? In Attack on Titan, most titan shifters are only shown in their titan form for a while, but apparently, Pieck can stay in her titan form for up to 2 months.
How long can a titan shifter stay in a titan form? What about Eren?
Note: this is not about the 13-year curse, but the duration of the transformation.
Although I am an AOT enthusiast, I, too, am unsure. If you count Annie in, she was in a dormant stage for 4 years since her capture and Eren's rumbling. I'm assuming she was using her titian powers, because it would have been impossible for her to stay alive without suffocating, starving, and dehydrating. However, When Ymir was given the Titan power, she roamed outside for a while before going into a hibernation state for around 1,800 years all the while remaining in Titan form the entire time. Since Eren has inherited Ymir's powers, I'm assuming that he can at least last around roughly the same or half the time, but only if he went into a hibernation state like Ymir. This is all speculation on my part, however, and the time cannot be actually determined.