Tank
With World War II the multi-turreted tanks proved impracticable, and as the single turret on a low hull design became standard, crews became standardized around a crew of four or five. In those tanks with a fifth crew member, usually three were located in the turret (as described above) while the fifth was most often seated in the hull next to the driver, and operated the hull machine gun in addition to acting as a co-driver or radio operator. Well-designed crew stations, giving proper considerations to comfort and ergonomics, are an important factor in the combat effectiveness of a tank, as it limits fatigue and speeds up individual actions.
Battalion
Prior to the late 1980s, Soviet tank battalions consisted of three tank companies of 13 T-64, T-72 or T-80 tanks each, along with a battalion headquarters mounted in a command tank and a headquarters and service platoon, for a total of 165 personnel and 40 tanks; battalions using the older T-54, T-55 or T-62s tanks had 31 or 40 additional enlisted personnel. However, forces in Eastern Europe began to standardize to a smaller formation with 135 personnel and 31 tanks total, with each tank company consisting of 10 tanks total.