That's the problem though. Even if most people are offline during the night or during holidays/weekends, you still need to provision enough IP addresses for peak demand. ISPs aren't paying for IP addresses by the hour, they're probably leasing/buying subnets on a yearly basis, if not longer.
Your phone doesn’t sleep, its always talking to Apple or Google. IP addresses are rotated to keep trouble users at bay. Just like qos isn’t really saving on bandwidth costs.. if you download via http you’re gonna get full transfer speeds available to you, but a single BitTorrent connection won’t. It’s all about mitigating power/problem users
Maybe 10 years ago, but these days just about every Internet-connected device talks constantly.
So they would have to be not home, and not leave any IoT device on when away. Of course this happens, but is probably very rare in the evenings (and at night).
