Is castle_interrior_assault.sco ever used?

[Frossa]

Like every Town, every Castle in WFaS has an interrior(sic)_assault scene, but is this actually ever used in the game? It's possible to "break in" into Towns if you have a certain cavalry ratio, which triggers the Town's interrior_assault mode, but I can't see this option for Castles. I'm currently modifying some Castles' environments, and I need to know if it's worth the effort to bother with their interrior_assault versions.