Door open or not - there was not enough operational mobility to compensate for the defender's interior lines (intact and uninterrupted rail-road network). That's why the offensive had no regular Schwerpunkt.

It was simply not about manoeuvring on large scale, but about pushing to opposing armies towards collapse.

Besides; nothing beyond the first day could possibly be planned. There had been no sustained breakthroughs for three and a half ears on that front.