Repair of transport several people at once (Battlefield 1)

Friends tell me.the soldier class support.it has an option of repair tool.with this option it is possible to repair your equipment and Vice versa to damage the enemy.but the description is still not clear given - that when one car is being fixed by several people that the effect of the repair is weakened.
There do not understand,in fact the opposite is logical the more soldiers support around the tank and they are all trying to fix it, the repair would have to go.