It's probably limited to 8 hours because end user could forget they have it enabled/ forget to disable it, then create a support case to Google when a device on their network has poor performance. Would be my guess. 🙂
You can provide this as feedback through the Google Home app.
I just wanted to jump in real fast to see if you saw olavrb's reply and to see if you still needed some help on this or if you were able to get it sorted out. If you are still needing some help, just let us know and we'll be happy to continue helping.
I wanted to follow up and see if you are still in need of any help? Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.