I'm not convinced about the warm oil idea, the prop hub oil does not circulate, it only adds or subtracts a little oil to change the pitch a little bit during normal flight operations. The propeller hub oil temperature must certainly be very close to the ambient air temperature.
I have upgraded the blades on my Yak-55, which included removing the propeller pitch dome. Inside (after the expected liter of oil poured out) I found a ring of carbon crud. This is centrifugally deposited and lays next to the oil seal. Every hydraulic constant speed propeller must be like this.
The oil enters and departs the hub thru a tube in the center, so carbon deposited must be manually removed. The fewer times the prop is cycled, the fewer times carbon is deposited.
I cycle the prop twice before take-off because I want to know that it works.
I'll probably remove the piston dome on the next condition inspection to inspect the parts and clean the carbon out.
a link to the monoplane forum where I have a few pics of the prop blade upgrade and the carbon inside the prop pitch actuator.
EAA 668340, chapter 326 & IAC chapter 67
RV-8 N89SE first flight 12/26/2013
Yak55M, and the wife has an RV-4
There is nothing
-absolute nothing-half so much worth doing as simply messing around with Aeroplanes
(with apologies to Ratty)