F--king with the engine to automatically make battles take longer for the sake of Stalingrad is making the same unbalanced mistake that WiF and TRP made.
Sake of Stalingrad?
There were plenty of sieges and long-term battles of attrition during WWII.
Battles of annihilating pockets, assaulting cities and general fortification fights generally lasted a LONG time if assaulted in the wrong way. It took the Allies months to get around the Siegfried line, simply because of the fear of such a battle.
The Warsaw Uprising of 1944, the Siege of Leningrad, Monte Cassino, the Italian fortification lines, the battle for Papua (depicted in HoI2 as the fight over one province, the Owen Stanley Mountains), battles for Guadalcanal, Tarawa, Iwo Jima, Okinawa and the Philippines, as well as the Burmese campaign - all were extremely bloody and long-lasting battles which all, in their own way, had a massive impact on WWII.
While it is nothing like World War I's meat grinder, WWII had its own way of adding to the death - these battles, while not on the scale of the Western Front, consumed huge numbers of lives.
There needs to be potential for a grinder - it just needs to be lodged in reality. Armour would not grind against infantry on an open plain unless the infantry had Maginot-style fortifications. Airborne troops waiting for reinforcement will hunker down and defend every inch - in the words of many, especially following Bastogne, "We're airborne! We're meant to be surrounded!". Mountain troops should be the same.
And remember, HoI3 won't have the mass stacks of HoI2 - thus helping the sense of a battle across multiple provinces.