In episode 17 of Attack on Titan season 3 part 2, when Levi takes out the Beast Titan's arm, eyes, and legs, Levi is in the air above the downed titan. When Levi goes for the kill, Zeke says that he doesn't have enough time to harden his nape. (YouTube video)
Levi was in the air, reeling in towards the Beast Titan. The ODM wire was still taut but the ODM gear was set to reel speed. It's demonstrated time and time again that when people using the ODM would listen to the order from the captains/whoever was in charge, they all move at the same speed and don't seem to rehook. They just stay there.
We saw Annie/the Female Titan harden quick enough to be protected from Oluo which was really fast.
But back to Levi, there wasn't any tall freestanding objects insight, so how did he move so fast? Please don't say it was gravity. He wasn't falling, he was reeling.