What's so big deal in all this 3h vs 24h? It is still downloading it only once anyway and if there is no update the network call it makes is really 300 times mo

What's so big deal in all this 3h vs 24h? It is still downloading it only once anyway and if there is no update the network call it makes is really 300 times more lightweight than opening google.com. I really don't understand this.