From what i learned learned in school if i only power one wheel the board would go in circles but why isn’t this the case?
Only 2 wheeled vehicles, like a Segway, will turn with 1 wheel drive. Multi wheeled vehicles don’t work like that. If you have a 4 wheeled vehicle, 1 wheel drive works perfectly fine. Most cars have an open differential, which sort of makes them one wheel drive. For the skateboard, you would only spin if the 3 non driven wheels manage to suddenly lose traction and the drive wheel manages to keep it (which is probably impossible) and even then, your balance on the board will keep it going in a straight line. So bottom line: don’t worry about it.
In the end it depends on the user and the environment. I have driven just one electric skateboard with a single drive and personally I don’t like it. Usually my track includes hills, hard acceleration and strong breaking. I’m feeling the influence from a single drive and don’t like that it has less traction while breaking. You push and pull just on one side of the axle and it will give you small amounts of steering. I call it torque steering from now.
Again I use all of the power while breaking and accelerating and when you live in a flat area maybe it’s not that present.
It also depends on the motor. I have a 2700W motor, which is an enormous amount of power, accelerating or braking.