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.
Platoon
Tank platoons prior to the late 1980s consisted of a platoon headquarters squad and three tank squads, each consisting of one T-64, T-72 or T-80 tank for 12 personnel and 4 tanks total; platoons that used the older T-54, T-55 or T-62s added another crewmember for a total of 16. However, tank units operating in Eastern Europe began to standardize their platoons to just two tank squads, for a total of 3 tanks and 9 personnel.