What is the advantage of building a legion in battle compared to the Macedonian phalanx?

The fighters in the phalanx had to constantly keep a tight formation, so any unevenness in the terrain led to its violation, and enemy soldiers could penetrate into the phalanx, where the long spears of its fighters became useless.

The legion had a more flexible structure, it could be divided into separate groups of fighters, overcoming difficult-to-pass areas, although this required greater individual training of the soldiers – after all, they did not feel comrades next to them.