[rich_sasha]

My kiddos have had low but positive screen time and knew the alphabet quite a bit earlier.

My personal impression is that while there's deffo stuff kids shouldn't watch, the thing that matters is what the kids do apart from TV. If it's nothing, or insufficient, it will be terrible. If as well as screens kids get plenty of high quality attention, the outcome will be good.

You could argue, and I'd struggle to disagree, that less screen time is always good. But there's tradeoffs in this optimisation. Parental attention and energy are also finite - unless you're super rich, have 3 nannies, a chef and not working. At some level, giving the poor overworked parent a break by sticking the child in front of a screen for a bit might mean the parent has more energy to do something worthwhile with the kiddos afterwards.

There's a nice statistical experiment in it no doubt - child outcome as function of screen time, high quality time and "fend for yourself" time, controlled by how much energy the parents have - will the coefficient on screen time be negative? Merely zero? Maybe even positive, just smaller than the other ones?

But good luck getting the data, never mind randomisation.