If it's an EPA-approved (afterburning) unit, and doesn't use a
catalytic converter, it's simpler to manage the fire so that the
secondary combustion flames stay lit at as low an output rate as
possible, until all the volatiles are gone. That'll give you a clean
burn and best efficiency.
Fact is, current woodstoves don't have an ideal stack temp. They can be
run cleanly over a wide range of output, often with little variation in
efficiency- as indicated by stack temp. Local dealer advised me to put
the thermometer on the top of the stove to indicate output, for this
reason. Now I just use if for decoration and tracking startup.
To keep it clean, keep all the internal fires burning, especially the
one where the secondary air is admitted.