What our long departed and much admired
411A had to say.
Having flown DC-3's, DC-6's and Lockheed Constellations in the past, can say that ALL of these aircraft were climbed slightly high (100-200 feet), then descended slowly to the desired cruise altitude, while maintaining climb power.
Once level at altitude, reduce to cruise power (approximately 50% BHP) and adjust mixture to autolean, close cowl flaps and oil shutters as needed...presto, time for coffee.
ANY other method of level off at the desired cruise altitude took MUCH longer to reach the desired cruise speed, simply because these aircraft, as well as many older turboprops (F.27/FH227's for example) did not have excess power at higher altitudes, unlike many turbofan powered aircraft today.
What Exactly Is, "Flying On The Step"? - Airliners.net
Where does lack of excess power put you on the drag curve?
Talking of the U-2, did you know in the cruise the power was at idle.