An infantry division during World War II, it was the combatants who really fought on the front line, and the number of combatants was not large. Generally, it accounts for about 60% of the whole division. An infantry division of 8,000 men with a combat crew of 4,500-5,000 people. That's why only these people are sent across the river.
According to the usual calculation method, if a division loses one-third of its combatants, it will be regarded as a heavy loss, and it must be withdrawn for repair, otherwise it is easy to lose the whole structure, which will affect its combat effectiveness.
According to the standards of the German army, the infantry division that attacked the barricade factory lost dozens of soldiers and a few officers in a day, even if it was a heavy casualty. Although it may not seem like much, as long as such casualties last for a week or two, this infantry division will basically lose its offensive capability (because some of the fighters have to maintain the battle line and wait for the follow-up troops to take over, otherwise that little success will be lost)
It is worth mentioning that the German army was surrounded at Stalingrad, largely due to the lack of heavy equipment such as anti-tank weapons by the client state troops that formed the flanks, which led to excessive casualties and a direct breakthrough of the line by Soviet armored forces.