Two aircraft that I have flown previously, the DC-6 and the F.27 (and FH.227), achieved much better cruise performance if climbed (for example) 200 feet higher than the desired cruise level and then slowly descended while accelerated to the desired cruise airspeed. This works for light piston twins as well, especially if at higher weights.
It may come as a big surprise to the younger set to realise that large 4-engine recip aircraft were always cruised at a constant power setting rather than a constant airspeed, unlike jet aircraft.