If you look at the CDS for the schools she’s considering, you’ll see what the breakdown is for each section of the test. At many of the very selective schools, a 620 in math will be below the 25% range. (I am not familiar with the UCs on this front.) If it was timing, she can get faster with practice. If she mostly slows down on the harder math but can do the easier math quickly, the ACT could be a better test. BUT practice is very important on that one. Given how good her other stats are, it could be worth her time. Then again, she will be a good candidate for plenty of schools, but perhaps not those, with what she has already. It’s really a question of what the goal is.