You don’t even need cover the debate subject to win, if you can convince the audience your opponent is an idiot.
In highschool (which is a very long time ago), I was woefully underprepared for a debate. My opponent not so much. He made some very good arguments. Unfortunately, he made a fatal mistake with his opening, “Good morning”. It was the first period after lunch.
That allowed me to eviscerate him. If you don’t even know what time of day it is, how can you possibly know anything about the subject of the debate.
I won the debate handily. I barely touched on the actual debate subject.
A show of hands. A couple of my opponent’s friends voted against me, but the rest of the class voted for me.
One of the friends complained that I hadn’t stuck to the topic, but the teacher sided with me. It helped that I’d been on the debating team in lower school and had seen other debaters treat mistakes in a similar manner. Having a drama teacher that loved theatre sports (which was relatively new at the time - at least where I lived) also probably helped my improv skills.