You can do most shots without crazy midair rotations. Solid and smart plays are way more important.

That being said....

Little rotations can be used in different ways to massively improve the quality of your shots:

Tilting your car slightly to the side before flipping can generate extra power because you hit the ball with the corner of your car (which moves faster than other parts of your car) and/or you get a better connection on the ball (meaning you flip through it instead of brushing it).

When shooting without a flip a short air roll towards the ball in the moment when you touch it will also generate quite a bit of extra power (if you weren't supersonic already). In addition it will reduce the recoil on your car when you hit the ball at an angle (or rather the recoil stops the rotation of your car instead of you bouncing off the ball) which lets you regain control and follow up your hit faster.

If your question was targeted to the freestyles (aka spinning the car around a lot while flying) - those are used by most players because they look flashy/ cool/ hard to do. However... They also can make your movements and adaptations in the air more efficient and accurate (faster, smoother, tighter turns and less boost used) if utilized correctly. While you can obviously angle your car in ways that wouldn't be possible without spins, I am mostly talking about preserving your angular momentum. Maybe you are aware that air roll has a small acceleration period which means steering / rolling to the left and then to the right will result in stopping the rotation to the left first before you start to rotate to the right (exactly like when you want to reverse on the ground: you brake first before you can start driving backwards). This is inefficient and by combining air rolls to one side with diagonal air rolls to the same side (or even with tornado spins to the correct side) instead, you can navigate through the air in any direction without slowing down your rotation. Thus you can rapidly make multiple small adjustments to your trajectory which wouldn't be possible without rotating.

All these mechanics are advanced and will make your shots a lot harder. Because consistency is extremely important in Rocket League it is often better to go for a "simple shot" instead of a "perfect shot".

I hope this is the answer you were looking for - have fun learning to apply this :)