Genesis of the Daleks - S12-E4
Trivia: The actor who played Davros, Michael Wisher, always wore a kilt to the studio, as he preferred it to trousers. It is never seen, of course, as his lower body is always hidden inside his Dalek chair. (Source: DVD commentary).
Answer: In 'The Five Doctors', three separate Cyberleaders are definitely used. So it's likely that Cyberleaders are like unit commanders, of which a fair-sized army might have several.
Daria Sigma