If you talk about efficiency this way, please rethink what efficiency means:
(Power-out + loss)/(power-in) = 1 If you know how to define power out and power in, you know how to define prop efficiency. Thrust is only part of it, but it means nothing without speed. Speed all by itself also means nothing. Enter time as well to transfer work in power, and you are getting nearer.
No more talk about efficiency please. A boomerang is more efficient than a wooden stick, but that is all that can be said here, and still it has no relation whatsoever to static thrust.
An air brake does not need to be efficient, yet it can prevent your engine from spooling up. A plain stick will do that. The best prop with the best foil for lift to drag ratio will also act as an air brake, but it will provide more thrust than the stick does. Enter airfoil here. All airfoils which have a depth greater than their thickness, represent something better than a stick. Not more efficient as a brake, but with ability to provide something more than drag. So there must be a shape that provides excellent thrust at static conditions. Not very effective in flight perhaps, but it will have best efficiency (efficiency!!!) at low speeds. Other foils will have less thrust and more drag at static tests, but will have the efficiency at higher speeds.
That is why static tests are called useless by some. I think that depends on what you want to know.
I use the static thrust because it allows me to define the engine, and evaluate all the changes I want to make in lieu of tuning etc. Flight characteristics come close if the flight prediction is anywhere near OK. Not good, but just OK.
It still needs not a fistfull of props, but props near the prediction to get best flight characteristis.

If you staid with me this far, I hope you will never talk about efficiency of a prop again. All props are efficient under the right circumstances. Performance yes! That is a different story.