That is NOT correct.

2, 3 or 4 blades it makes no difference.

HOWEVER, SOME ( notably the Hangar 9 PTS ) trainers come with a special fairly oblique low pitch 3 blade prop.

The prop acts as an air brake when you bring the throttle to idle, making it easy to slow the plane down.

That is why they are standard in all of the PTS series of planes, including the Alpha's, P-51 PTS, etc.

Some ( misinformed ) people poo-poo these props, because they are so used to their higher pitched, larger diameter props producing far more power, that they assume that these are no good.

However they are perfect for what they are designed for... newbie pilots flying an otherwise reliable setup.

When used on the PTS Alpha as designed, they help slow the plane down during landings, and in flight making it easier for the neophyte to control the plane.

You, or they are mistaking the PTS 3 blade prop and ALL other 3 blade props...

They are NOT the same.