Western army cannot support 5 axis invasion. certainly not street fighting in built up areas against hostile population without months of airstrikes. there is no comparable example.
Western army would never consider a 5 axis attack, and would consider such a move wrongheaded.
To understand why the western army would not want to do it while the Russian army would, it has to be understood western and Russian armies generally has a different operational ideology, for the lack of better word.
Soviet operational doctrine since around 1943 has emphasize opening at battle with a style of practical military deception operation called moskirovka. Moskirovka presumes Soviet forces had numerical superiority. It emphasizes setting the stage for the main decisive attack by first simultaneously attacking the enemy along multiple widely separated axis that makes it difficult for the enemy to know where the main attack axis lay, and also makes it difficult for the enemy to be able to position its reserves so as to be able to advantageously meet Russian attacks on several axis at once. This forces the enemy to guess which axis is the main one, and commit their reserves prematurely. Only when it becomes clear where the enemy has committed their reserves, would Russian select the primary axis of attack to avoid enemy reserves. The Russian army would then commit its own reserve to achieve a breakthrough by effectively push against an unlocked door. During the late 1943-1945 period, the Soviets implemented moskirovka with tremendous success against the German army. Despite later soviet portrayals of great soviet heroics in beating the german army, the Soviets didn’t do much out fight the Germans as out deceived and out maneuvered the German army.
Moskirovka remained an integral part of soviet operating doctrine through the Cold War.
It looks very much to me like the Russians in the current Ukrainian war also attempted to implement a version of moskirovka. The problem is the Russians didn’t start the battle with any numerical superiority. So the Ukrainians were able to check each of Russia advances and stop all of them from making decisive breakthroughs. If the Russians had done it right, then Russians would attack with so much force that each of its 5 attack axis could potentially break through into Ukrainian hinterland, and Ukraine must gather the balk of its reserve to meet any single one of them. Once the Ukrainians have committed to meeting a single one, the Russians would then throw in their own reserves into an attack that the Ukraine did not deploy their reserves to meet, and break through. They obviously failed.
Western military thinking says advantage of concentration of force outweigh any advantage in deception resulting from dispersal of forces. So western military strategy would looks for 1, at most 2 main axis of attack, and strive to achieve overwhelming superiority at the single or at most two points of attack. Western concept of military deception does not emphasize actually going through the motions of attacking at different locations similar to soviet Moskirovka. Instead it emphasize deception before the battle through camouflage, false signals, False units etc. Deception during the battle would be achieved by depriving the enemy of situational awareness by destroying their surveillance assets such as reconnaissance planes, and then maneuver the main attacking units in unexpected ways so as to attack along axis the enemy did not come to expect based on pre-attack intelligence.
So you are right, the western army would not attempt to attack in 5 direction at once. They would consider that a serious breach of fundamental military principle of concentration of force.
Russians did attack in 5 directions at once as they have their own idea of fundamental military principles that had worked many times before. But they clearly did not make sure the circumstance that made such maneuver succeed before is duplicated in Ukraine before they tried.
