I understand the point about taking a test in the summer prior to junior year, assuming the student has had at least algebra 2.
I also believe prepping for and taking the SAT can be good practice for the PSAT…especially if becoming an NMF is important for the student financially speaking (in which case prepping and taking practice tests is a must).
Many athletes who want to be recruited take a test prior to junior year/early that year too, because recruiting at some levels starts in earnest at the beginning of jr year.
I wouldn’t suggest continuing to test if a good score is achieved.