I know a girl who is applying to Harvard EA and is getting six rec letters, totalling between 17 - 20 pages. I’m applying ED to a different school, and my teacher/counselor are only planning on writing a one page rec letter. At what point is it too much?
Do not send more than the school allows (they usually say on the website). That will just annoy admissions. “The thicker the file, the thicker the student.” Harvard actually only asks for 2 teacher letters. And how would this student know how many pages of letters they have? It is recommended that students do not see their letters; schools that know they did tend to discount the letter contents because the teacher may not have been honest.
If a school has a minimum or recommended number, at least have that many. A counselor and teacher rec are not the same. Counselors have a specific form to fill out under the Common App, and can add written info if they know the student well. But that does not substitute for a teacher rec if the school asks for one or more of those.
One page is fine. 2/3 of a page is fine. Content matters more than volume.
Six letters at 3+ pages each won’t seem very smart. An individual applicant is charged with making his/her own best decisions, not throwing it all against the wall, to see what sticks. She is responsible for deciding the number she sends. This will reflect on her.
Now, your own task is to do your own best, OP.