At this moment, Gojo was barely keeping it stable. The spell, Thunder Step, costs a lot of mana to start up, but to keep moving, it only requires very little mana. But there was a catch. All things in life have a catch, and those problems are what the entire solution is built around.
The catch of life is death; being born is the moment your clock to death starts ticking. Getting a job also has a catch, and it is that your employer would eventually be making more money off your back than you do. Getting married comes with responsibility, and even eating means you have to shit something out eventually.
In the spell's case, the higher the speed target he wanted to reach, the costlier the acceleration to get that point became, simply because the magnetic field would need far more energy. That would make it less and less usable and more of a waste.
