WOT...let it run!
Not really the same but I had a C-421 with Continental GTSIO-520's.
Ran it hard all the time after speaking with one of the original engine designers...
Those "troublesome" engine ran 800 hours BEYOND TBO with NO issues...
Completely agree. Run them hard, often, and they'll continue to do that.
Leok, throttling back for slow flight, or local cruise/sight seeing/joy of flying flight is understandable, but that would be the only time I'd agree.
If you're taking off to go somewhere, running at WOT to altitude, with proper mixture management, will generally be an incremental
reduction in cost. Not only is the throttle volumetric flow more efficient, the higher MP pressure will result in a higher cylinder pressure leading to a more efficient combustion. It also reduces the time to climb and getting to cruise power/speed faster. It's a higher fuel burn in the climb, but with less time in the climb, you'll be at cruising altitude with a lower cost per mile sooner, reducing block-block costs - and time. You can pull back the RPM if you want, but leave the throttle full open.
Not directly a take-off power setting, but another consideration is your Carson Speed, which is the most efficient speed for the airframe based on 32% increase over best L/D speed, generally best glide which for the -10, ~ 85KIAS, making the Carson Speed about 112KIAS, which is why 110-120KIAS climb speed is fairly efficient.
Noise is a non-linear squared function, so if you're concerned about noise at lower altitudes, then getting up high and away from the ground faster makes more sense to reduce your noise the fastest, in addition to changing headings away from population as soon as practicable. Once at cruise: WOT, RPM to suit desired power/speed, and the adjust mixture appropriately. If that's still too fast for your taste, pull back the RPM and readjust mixture, but leave WOT.
If you want to reduce RPM, ok, but just realize the higher the RPM, the higher the horsepower, and most folks fly airplanes to go places, generally fast (a function of "total performance") - and more horsepower will produce more speed. Whatever you do there, just leave your throttle full open and you may find not only better performance, but overall efficiency too.