We have always had spiral integrated maths BUT from what I can remember you did a whole chapter on each topic drop start to finish each year - you didn't jump round and it was the 70's so while it was "new maths" the formatting was fairly traditional.
Ds6 on the other hand is learning to carry out a statistical investigation. Why? He is supposedly fully challenged by this and his basic maths facts homework. But statistics is maths for people whose skills are not in maths and really requires more life experience. Why can they not learn the four operations, fractions and decimals first then move on to such topics? And they don't write anything down so a lot of the stuff they do tests their working memory more than their maths. Ds has a ludicrously high working memory to be fair but what about everyone else who could do it quite fine with manipulatives or on paper but not while staring at the wall?
