I'm seeing a lot of different answers on how long a myo card can be. I have seen people say they could fit an entire Harry Potter book around 24 hrs long on one card and others say no longer than 5 hrs. Can Yoto answer this? I would love to use Yoto for a middle schooler as an option for listening to audiobooks without needing a digital device such as a phone, tablet etc. Issue is a lot of books for older kids are longer than 5 hours. I would hate to have to split some of these books into like five cards. Any help would be appreciated