During their tuning in the factories, many tanks could hardly be considered finished products due to the limited testing time available.
When the tanks arrived at the front, some were damaged when they were unloaded from the trains.
During combat, some were hopelessly abandoned to their fate.
These problems occurred during the first appearance of these same tanks. But when those that could be returned to the factory were repaired and brought back, their improved performance was significant.
A tuned tank was much easier for its crew to control. Given that the vehicle's performance could mean victory or death, the more battles a tank survived, the more legendary it became. This is why some tanks were able to see the front on several occasions despite being damaged, and were even looked upon favorably when they were repaired and returned to combat.