This student explains the strategy he used to increase his ACT score. https://www.collegeconfidential.com/articles/how-this-student-brought-her-act-up-by-4-points/
Being honest, I have to say “Duh!” This student’s first action after getting his score report back from his first test should have been to scrutinize it and see where his score was low.
Using an app twenty minutes a day is only going to be useful pretty much to students who are just looking for basic test taking skills, not for a student who wants to score in the 99th percentile.
I would have guessed that small gains (like four points over time and repeated testing) would be somewhat the norm- is that not the case? My daughter’s score went up nine points after she took a few full length practice tests.