Are slow flyer props a must for quads?
I was wondering why most of quads have 9 x 4.5 or 10 x 4.5 or 4.7
Can i not use a 10 x 7 or 9 x 7 prop on my quad.
is it necessary to use a slowflyer prop on any multirotor?

Good question was wondering myself . But i think its on you

lol i guess its a common query.

Slow flyer props help with efficiency. You can think of the prop sizes as gear ratios. For multirotors big lazy motors are preferred as they can swing big low pitched props with ease. Th emphasis on slow props is because when a prop is rotating very fast, the efficiency drops. This happens as the the blades do not get clean air to push, i.e., a fast prop blade creates turbulence and the second blade of the propeller enters that turbulent pocket of air and produces less lift(thrust).

To make up for their slow rotation speed, slow flyers have a bigger surface area to displace more air.

For pitch and prop size: Pitch = Speed   Prop Diameter = Thrust (and Acceleration)

If you use a bigger prop you have to use a lower pitch and vice versa for some specific motor (so that the amp draw remains same)

In conclusion, you may use what ever kind of props you like (keeping within your motors limits). Like instead of using a 10X4.5 you may chose to use a 9X6 prop. Your efficiency will drop but top speed will go up.