I really think that everyone that is trying to manage 2 types of tests should focus on 1. SAT is more wordy - everywhere (English and Math) so if your kid is not a critical reader or gets easily tricked (like my youngest) …they should focus on ACT. ACT is way more time constrainted, so if that is a huge issue, focus on SAT. Both tests can be learned… They have to KNOW IT, what types of questions, why they got each question wrong, etc. I really don’t think switching tutors or these Magic online tutors are going to be the make-or-break. Honestly if they do 1 subsection per day (out of the 4 on each test) and spend the time reviewing why they got things wrong, that is what really helps .
I am just a parent like all of you but I was able to coach my kids with basically just the books and online ACT prep and Khan (initially, for my eldest when he was trying to figure out which test works for him). My D prepped a lot. 4-5 hours a week for about a month last summer, then maybe 1 hour a month through the fall, and then 3 hours a week for 3 weeks over Christmas break. She went from a 27 pre-ACT to a 29 ACT in February to a 32 ACT in April (she went back to 3 hours a week for 2 weeks in March - only focusing on Math and Science which were her weaker scores and most teachable). Superscore 33. We used tons of released tests that are available online. Just the sections that needed work - she was naturally great at the grammar, so never touched that one except in a final full practice test.
My last strategy is my own and I’ve never read about it anywhere, but I believe it- take whichever test you’ve decided is the best one (SAT or ACT) in consecutive sittings. Feb/April/June or June/August/October. Don’t skip. Why? The curve changes with every sitting and I’ve noticed that the usually follow a tough curve on one section with an easier curve on the same section in vice versa. I feel like the easy tests (with tough curves, probably like this June SAT) are much harder because if your kid makes a few stupid mistakes, they lose a ton of points. If they take it consecutively, they have a better chance of getting a different hard section from the previous time they took it, so could end up with a more favorable superscore.