For years I tried limiting the screen time of my kids (back when iPhone was at versions 4 and 5). Never could manage to do it properly. My kids would always hack it. I concluded that Apple's interest in having kids spend as much time (and money) on the phone is opposite to mine and that's why they didn't allow proper parental controls. Now I just ask for the phone in the evening and give it back the next day. So much for "high tech". Seems that Apple finally woke up and did something about this. Asking a kid not to abuse the phone is like putting a large bag of chocolates in their room and saying "eat responsibly!".