So an admissions representative told me a few days ago that they only read letters of recommendations from high school teachers and they don’t consider anything written by anyone else… is this true? What’s everyone’s experience with this?
Well, they require a counselor recommendation as well. If you mean do they consider recs over and above the teacher and counselor evaluations, then the answer is no. If you mean do they accept a rec in lieu of a HS teacher rec, unless you have some alternative educational experience outside the traditional HS, I’d jut give them what they ask for.
I submitted five letters: one from my HS counselor, one from an HS Social Studies teacher, two from teachers at my postsecondary institution and one from my music instructor. I attended a performing arts post-secondary level academy after HS (noncredit, so im a freshman, not a transfer) and since i’m applying to a theatre program I thought that the letters would provide good insight to me as a performer/artist. The thing is that the letters from my postsecondary teachers and my music instructor are absolutely glowing and full of praise, 10/10 I’d say, while the letters from my high school are just good in comparison (7/10 i’d say). I’d really hate it if they read those letters only and not the amazing ones my other teachers wrote 
Also I read a lot on this forum about people sending additional letters from all sorts of people (employers, etc) that aren’t HS teachers, so I was surprised when they told me they don’t even consider them…
That was probably your first mistake. For colleges that accept additional letters, I generally suggest sending only one additional, since after a while, the glowing comments just get a bit repetitive. Unless the additional recs add some insight to you as a person that was not covered in the other recs, it’s just more paper. At some point the old adage kicks in - the thicker the file, the thicker the kid.
Still, I hope it works out for you. Good luck.
Actually, the letters are not all the same. They all cover different aspects of me, and they aren’t very long. My Social Studies teacher talks about me in a regular classroom environment (non-theatre) and how I expressed a strong interest in social issues. The one from my music instructor is more about me as a person rather than a student (he knows me since I was born and is a close friend of the family). The ones from my postsecondary teachers: one is about my talent and potential for success, the other about my work ethic in class and my relationship to my classmates and teachers. I never read the one from my HS counselor, so I can’t comment on it.
Anyway, if they only read the HS ones, it’s down to two letters only, not five. So I guess i’m good. I actually just posted this because I was curious if anyone else knew about this rule.
On Common App did they allow you to add more letters of recommendation or was there only space for two? If they allowed more they will probably read them if they are on the fence about you especially if they concern the major you applied for, which it seems like they did. If they’re for sure accepting you after the HS recommendations then they probably won’t read the rest, but the extra letters won’t get you in if the rest of your application isn’t the right fit.
Hmm. When I asked them if one of my teachers could contact them to correct an error in their letter, they told me to not even bother because they’ll never read it anyway. I don’t know. It’s all done anyway, so I guess now it’s just wait and see. Just though i’d let everyone know about this before they consider asking someone outside of HS for a letter! 
I applied ED1 (was accepted) and had asked my admissions rep. what to do if I had an extra rec letter. I had a letter from a college professor from a summer program I had done. They told me that I can have the letter emailed to the Admissions Rep and it would be put in my file. Hope this helps and good luck everyone!