FWIW an older thread with some decent discussion beginning further in, more like post 33 (biased as I am :))
Redshirting not only has no measurable impact on PhD achievement, it also has no impact on post-graduate income. As noted above there is little to no evidence of long term benefits and there is some that suggest some long term harms. The premise of redshirting taken from hockey, that it places them on a trajectory of getting the starting positions, the extra attention, and the extra resources as the higher performing one, do not apply in the same way.
Who really cares if a child does marginally better on standardized tests so long as it isn’t the ones needed for college entrance or later?
Of course if a parent has a strong sense about their specific child there is room for flexibility, but the default should be the default.
I would also argue that parents trying to make the decision based on where their child is at that particular moment socio-emotionally and cognitively is usually an unfair ask.
Development is very non-linear. Barring an actual disability, delay, or giftedness, the correlation between where a child is today and where they are in a year, let alone in several years, is not very high.
Spoken as one with an August birthday, one of the youngest and shortest boys in my grade throughout. And whose parents at KG entry were pretty sure was not all that bright.
Look, the ideal is to be in the middle of the pack. But you no more want your child to be the bored kid than you want her to be the one who has to work a little harder and who needs and gets a little extra teacher attention in grades KG to 3 to keep up with the pack.
I’ll add one more item into the mix. Gap years later on are more and more common. The norm for medicine now is to NOT go straight through but to spend a few years doing other things before applying to get some life experience under your belt. Add another year at the start too and it begins to add up! We’d like them eventually earning some money and saving for their own retirements …