What does your Flight Manual say?
Good point, I had a look...
One of the types I was referring to says:
"Gradually advance power lever, keeping the stick fully rearward until required RPM is achieved........ Normal takeoff may be accomplished at a lower power than the maximum allowed"
The Caravan says:
"Power - SET FOR TAKEOFF (observe Takeoff ITT and Ng limits). Refer to Section 5 for takeoff power". The Section 5 "ENGINE TORQUE FOR TAKEOFF" table states 1900 RPM, and provides a table "area" which includes a large range of power within torque and temp limits.
A few piston types I know (C 182, for example) are RPM limited for noise abatement by STC, so they are not developing full power at takeoff, using the Flight Manual procedure.
Others I checked do say "Full throttle" for takeoff.