More info on the ford/GM 10-speed trannys.
https://www.forconstructionpros.com/...peeds-too-many
The goal is fuel efficiency and smoothness (shorter spread between gear ratios). I suspect the benefits pulling a heavy load are less apparent with diesels like the Duramax/Powerstroke/Cummins, since the torque curve tends to be relatively flat between 1000 and 3000 RPM.