Film Theory (Matt) did a video on DBZ, an interesting topic.
If you don't want to watch it:
Frieza's 5 minutes until Namek blows up is 2 hours, 38 minutes, and 55 seconds of actual time.
Talking time between Frieza and Goku took up roughly 35 minutes, with 47 being from the actual fighting, and the rest from other characters, flashbacks, etc.
So why did Frieza say he only had 5 minutes if that clearly was not the case?
The theory:
Frieza knows how much time it takes to blow up a planet considering he has done it several times over the years. Namek is a VERY dense planet. Frieza realizes this after stating that it will only take 5 minutes to blow the planet up. Because he knows how to use strategies against his fighters, he used the 5-minute statement to get into Goku's head and stuck with it. Forcing your appointment to think they are on a short leash, so to speak, leaves room for error and panic. He knew Goku was stronger so he tried to get into his head, hoping he would make a mistake that he could capitalize on.
If you don't want to watch it:
Frieza's 5 minutes until Namek blows up is 2 hours, 38 minutes, and 55 seconds of actual time.
Talking time between Frieza and Goku took up roughly 35 minutes, with 47 being from the actual fighting, and the rest from other characters, flashbacks, etc.
So why did Frieza say he only had 5 minutes if that clearly was not the case?
The theory:
Frieza knows how much time it takes to blow up a planet considering he has done it several times over the years. Namek is a VERY dense planet. Frieza realizes this after stating that it will only take 5 minutes to blow the planet up. Because he knows how to use strategies against his fighters, he used the 5-minute statement to get into Goku's head and stuck with it. Forcing your appointment to think they are on a short leash, so to speak, leaves room for error and panic. He knew Goku was stronger so he tried to get into his head, hoping he would make a mistake that he could capitalize on.