When uncoupling a loaded semitrailer, after the landing gear makes firm contact with the ground, why does the AAMVA procedure call for cranking the landing gear a few extra turns in low gear?

AAMVA CDL Manual, Section 6.4.2 "Uncoupling Tractor-Semitrailers," Step 4, p. 6-9

Shifting some trailer weight onto the landing gear before disconnecting the fifth wheel reduces the force pressing the kingpin into the locking jaws, which makes the release handle easier and safer to operate, and leaves the trailer in a position that's easier for a tractor to back back under later.