Chinese "sign years" are a good example where it seems not to shake out. There's a 12-year cycle between repeating signs, but it doesn't seem that every 12 years you get whole cohorts of specifically intelligent/kind/diligent/cunning/lazy/science-loving/humanities-oriented/whatever children in a given school year, which will nearly universally be composed of only two star signs (Chinese New Year falling about halfway into the school year). It's even more obvious on the 60-year "element-animal" cycle that the world doesn't go 3 generations between people having "fire dragon" or "earth horse" characteristics.
It'd be hard to hide such statistical effects on an yearly interval, whereas the Western zodiac hides its predictive failures by not having signs that are commonly stratified into different groups.
It'd be hard to hide such statistical effects on an yearly interval, whereas the Western zodiac hides its predictive failures by not having signs that are commonly stratified into different groups.