More spread out with breaks less than two weeks equates to less knowledge loss ove break and equates to less time spent going over crap learnd last year. Retention studies basically blame summer farming breaks for kids losing like a third of what they learned last year. If thr first month or more of every year wasn't spent re-engaging kids or catching them back up to where they left last may, then the class would progress much faster. Now multiply that by twelve years in school.