FWIW, visited an Ivy last year, was told by admissions that they make two piles out of the applications.
Those that can do the work (high grades and SAT/ACT scores) and those that can’t do the work (low scores).
Once you are the one pile or the other does not make much difference in the admission process, that’s
where the EC, app essays, recs etc come into play.
All that said, 2nd tier private schools have formulas often heavily based on SAT/ACT scores for merit scholarships.
So if you want to go to a top school and can either pay or qualify for need aid, no need to retake.
If you are middle class, and need merit aid, then a 36 could get you more than a 35.
PS I read stats that indicated a VERY small % of people move from 35 to 36.
Higher your score, less chance of bumping it up. Intuitive yes, but the stats bear out what is intuitive.