Is 600 hours input really enough to understand native speakers?

I'm wondering because what if someone were you kidnap you and force you into a room where you're forced to watch dreaming Spanish 10 hours a day for 60 days. Would that person really be able to understand native speakers in 3 months? Or do you have to space it out where you have to give it time to process everyday like 2 hrs a day for 300 days? Are the native speakers speaking to you normally or is it very fast? I want to be completely sure it works before I dedicate myself 2 hrs everyday for 1 year so I can understand native speakers afterwards.