Pat, that is exactly the right answer.
Having done a lot of bow building, I can add to that, once the wood has compressed slightly (taken a "set" ), it has hardened quite a bit, and will resist further compression IF the bolts are torqued to the same specification time and again. This is the very max that the wood will stand in compression.
If the wood compression will not settle down, the initial torque was too high, and eventually the prop will fail.


I have spent a lot of thought on this, and came up with the following idea:
Wood being what it is, is very well suited for a prop, but is lacking in resisting the compression force that it takes to make a proper friction load to convey the engine torque without slippage and eventually breaking either bolts, or prop. The wood certainly will compress before non-slippage is achieved. Especially the "blond" wood, which is lighter, but also softer.
To make the wood compression resistant, steel compression tubes could be epoxied into the hub mounting holes to take the screw compression loads, and transmit the torque to the prop. Now the screws can be fully loaded to 80% of their strain limit without crushing the wood. The steel insert tubes will also enhance the centrifugal force integrity of the wood prop.