[hackinthebochs]

Here[1] is a good overview of studies on test prepping and their relatively underwhelming influence on scores:

>Once scholars control for all these factors as best they can, they find that coaching has a positive but small effect: Perhaps 10 or 20 points in total on the SAT, mostly on the math section, according to careful work by Derek Briggs of the University of Colorado Boulder and Ben Domingue of Stanford University.

[1] https://slate.com/technology/2019/04/sat-prep-courses-do-the...