I used these this summer for daughter and pupils. Most children proudly declared 5 to 6 minutes for time and scored full or almost full papers. I like them as a quick exercise to keep established skills fresh. They are about the level of Bond Assessment 10-11, apart from the cube ones which most can't do (I struggle with the occasional one myself).
On the subject of Athey, I no longer use them because many of my students (including very good ones) were scoring quite lowly compared to some very good performances in the others (****, AFN and NFER) so I felt they were sapping their confidence quite unnecessarily. I haven't used them for 2 years and it has made on difference.
****Edited in reference to rule 5 of the Forum Rules