What make prop? There was a time OMC let dealers buy SS props that were "semi finished" for the purpose of trying them on a customer’s boat to find the correct combination. This was for the bigger hp engines like V-4’s and V-6’s and stern drives. Once the size determined, the dealer could sell the polished SS prop to the customer. It was a sales thing so a customer didn’t have to buy a number of expensive SS props to find the right combination. These dealer props were finished just like the sales prop but painted red (I think powdered coated actually) and discounted to the dealer. They were not stamped "not for sale". Don’t know what other manufactures did.
My lake friend had a Cobia 19′ bow rider stern drive OMC V-6. When we tried the four blade dealer prop over the three he had, we not only gained planning speed quicker, but also held the boat at a better angle for tubing and such for the kids. The mileage got better cruising by 1/4 of a tank over a long ride, our lake is 10 miles long.
In racing it was always thought that you had to have a 2 blade prop, "there is less friction". Disproved when Vern Kargus won the 1976 Nationals in BSH at Hinton, W. VA. with a 3 blade. Go to a race today and Stocks are limited to only 3 blades, it would be rare to see a 2 blade. Mods are limited to 4 blades and that is what most are. PRO isn’t limited to blades and there are 5 and 6 blades, most are 4. The trouble with that many blades (5 or 6) is you can’t do a lot of tuning on the pitch as there is no room to hammer. Tunnel boats and offshore use a lot of 5 and 6 bladed props. It is just more effecient. Because we are in a surfacing position of the prop, there is more blade area in the water. Better control.
It has been always difficult to convince the pleasure boaters how important the right prop for a certain application is. One day testing props on an 18hp Evinrude, having the same coded prop, there was 2 mph difference between them! Conclusion, the accuracy of production props is not.