OVERUSE of the Borg. You do understand the meaning of the word 'overuse', right? If not, let me help you: it's using something more often than is needed or necessary.
"UNITY" was a fairly fresh take on the Borg with a planet of ex-Borgs. "SCORPION" was the first time the Borg got beat immediately by a legitimately stronger, better opponent.
If VOY kept the Borg encounters to just those two occasions, no one could accuse them of overuse. Which was the fundamental problem of the Borg on VOY.
"UNITY" was a fairly fresh take on the Borg with a planet of ex-Borgs. "SCORPION" was the first time the Borg got beat immediately by a legitimately stronger, better opponent.
If VOY kept the Borg encounters to just those two occasions, no one could accuse them of overuse. Which was the fundamental problem of the Borg on VOY.
