Bumping a Saracen type vehicle up a bank every mile or so is an old wives tale, yes it will temporarily relieve the wind up in the drive gears but they will wind up again in a very short space of time.
Suppose the tyres on one side are within 2% of each other, a not unreasonable tolerance for worn tyres. For each revolution, 2% represents 7.2 degrees, after 10 revolutions or circa 115 feet of travel it is 72 degrees and I doubt that even the most worn out Alvis 6x6 has anything like 72 degrees of play in the drive gears. Even with a 1% tyre tolerance the figure would be 36 degrees after just 115 feet.
Once you get to a corner and the 3 wheels on one side follow a slightly different track it gets even worse.