Shieldwalls and Schiltroms in EB timeframe

[JMRC]

Why should the schiltrom only be a formation for undiscipilined troops? As you mentioned it very natural and useful sometimes. Actually Sallust mentions one occassion in the Jugurthine war when Roman soldiers formed a schiltrom like formation when beeing ambushed and encircled.

Because if they are disciplined, I think they would be more useful in a shieldwall formation. However, maybe only the Training variable makes sense in this choice (EDU states that the "Training determines how tidy the unit's formation is", so a well trained unit will behave better in a shieldwall. I think...)