Story time with my DS used to be an hour plus a night when he was 2-3. I think he benefited from this enrichment, but how many wiggly 2 year olds are going to sit still while you read "Lion, Witch and the Wardrobe" etc? Probably not a lot. So I agree that enrichment helps all, but will help some a lot more than others. A sunflower will grow taller than a daisy if both are well cared for (both are nice and wonderful though).