It depends on which TM you look at. Maybe tightening the head more then once after installation was a common knowledge then for 1940s mechanics? At any rate, you have to have more than one manual with these jeeps. I found the answer on page 69, No. 18, TM 37-2810, March 1945.
“Caution: Cylinder heads should not ordinarily be tightened unless there is a definite indication of looseness or leaks. If tightening is necessary, use a torque-indicating wrench and tighten in the sequence and to the tension specified in the vehicle Technical Manual. When a new gasket is installed, tighten three times as follows: First, upon installation, second, after engine is warmed up, and third, after completing final road test.”
For the WW2 jeep you would follow the pattern as indicated in the graphic below:
See Cylinder Head Tightening Chart for more info.