One anecdotal story. My D19 took two SAT IIs in October but didn’t have time to study for them due to a heavy AP class load. They came back low
All her summer study time went into SAT study. But her SATs weren’t Ivy level (25% percentile for Ivies) and so when the December SAT came around, she took one last shot at the SAT instead of cramming for the SAT II thinking a better SAT was worth more than a better SAT II.
The only Ivy which required SAT II was Cornell (CAS). We didn’t send them to any other Ivy.
The gamble worked. She scored 100 points higher on her SAT and got into Dartmouth. Cornell rejected (even with Legacy) as well as all the other Ivies except a waitlist at UPenn.
She didn’t have any hooks for admissions. There are clearly other factors and no SAT II was not a deal breaker for us - at least at Dartmouth…