will schools factor in if I have not planned to enroll or commit to enrolled in their decision to pull me from WL? And does that mean if I get an A I don’t have to plan to enroll anywhere at all, as long as I don’t miss their CTE deadline? So if I get into shool A before April 30, do I need to plan to enroll them while I still remain hopeful for school b ?
Don't overthink this. You asked what you should do to keep the opportunity to go to your dream school B. That's what PTE is about.
Now, yes, putting down PTE is voluntary. That means that admissions offices need to tread extremely carefully with the information from CYMS. Let me go through how schools likely react to this information. Note: I am making assumptions on how schools use the information from CYMS, but I would not/never let other schools' decisions dictate how my alternate list works.
Let's play out a hypothetical situation. School B has not made a decision about you, but they get access to your CYMS status (you declare PTE to another school). You send them a letter of intent (as the school welcomes that communication) saying dream B school is your desired program. So theoretically, the admissions office knows that you (and others that may have sent in a letter of intent) prefer their program. They may feel more inclined to try to see if you are still interested (more surveys if you want to stay on the waitlist!) until they can act on the waitlist.
But now let's go to school A's desk. You may have responded positively to their initial offer but have not gone further with a commitment deposit. If you declare PTE to school A, their admissions team treats it as an UNOFFICIAL confirmation that you have acknowledged their offer. They will pester you more about their CTE deadline to confirm your seat in the class (and complete other tasks for financial aid, vax records, etc.).
BUT if you HAVE NOT selected PTE (seen as "PTE to your program")... You likely haven't sent any communications affirming your intent to attend A because your dream school is B (sent them a letter of intent) nor completed "homework" for financial aid, vax records, etc. The admissions office can logically infer you will likely not attend their school (even though you have no offer from school B). If they care about this signal, the admissions team will remind you frequently about the CTE deadline. They may anticipate that you will be a no-show and prepare to extend offers to others on their waitlist. The admissions team will pester about CTE declaration all the way up to the deadline. If you miss the CTE deadline, you get a "offer rescinded" letter the hour after the deadline passes.
In the ideal world where CYMS works, declaring PTE should affirm to school A that they should not start planning for you to ghost them on orientation day, and if you get an offer from B, you declare PTE/CTE with B to signal to A they can start moving to fill the spot in a professional way (you may have to still complete the decline-offer process by pushing a button on their portal or writing them an email). If you don't choose PTE, school A will begin to prepare for a mad scramble about your seat with at least three weeks to go to orientation... but it's better to do that now than during Orientation Week (which is what happened before CYMS). It's better for the alternates that are taken off school A's waitlist to move to school A with three weeks to go (scramble to get financial aid, vax records, housing, etc.) than to drop their lives and move with less than 24 hours notice (which is also what happened before CYMS).
This is the long way to tell you, it's a professional courtesy to all schools to use PTE. I don't remember if you are subject to an expected use/code of conduct with CYMS, but it is part of the overall AMCAS process where you did agree to professional behavior. Keep the admissions process sane and your chances to get into dream school B alive by using the PTE status on April 30 (which is the date when the information about PTE to other schools becomes visible to the admissions teams). It's not the most perfect system (LiaisonCAS does it better), but it is what we have.
Alternate TL/DR analogy: you can say you're dating school A, but at some point, school A wants a ring and wants to plan a wedding. If school B drops the bombshell that they want you, give your ring to B. Of course this analogy fails because school A will not act like a scorned lover... this happens in admissions enough to know declining an offer is not a statement against the school.
