It has been common advice given to parents to limit the time their very young ones spend using a smartphone or a tablet. It is so common that no parental control service or app worth its salt doesn’t come without some way to limit screen time. But new studies are surfacing challenging those long-held prescriptions. Some are even encouraging parents to let kids spend even more time fiddling with devices. It’s not a blanket recommendation though and it’s based more on how kids spend their time rather than simply how long they spend it.