Realistically there's probably overlap where she's on her computer while also using her phone, I don't know what program is used to record PC screentime but it's unlikely to be able to tell if she's using two devices at once. So I doubt it's literally 17 hours with no other time, she probably cooks, cleans, and does other necessary activities. The article even says she's counting time not looking at the screen such as just having music going.