Yes, my children are in grammar school. First: They focus almost exclusively on Math and Reading. Important subjects to be sure, but history, science, social studies etc are little more than an afterthought.
And as you said, a significant part of the begining of the year simply covers what was done the previous year. I'd prefer they simply provided a summer curriculum of 2 or 3 hours a week of such work if review is necessary, which would also eliminate the complete discontinuity from one scho year to the next. I'm fortunate that We can do so on our own, piecing together that sort of thing, but plenty of working parents have neither the time, or ability, or inclination to compose their own mini summer curriculum.7