I think even when the teacher can recycle the original letter, the administrative hassle of sending it multiple times for multiple students must get tedious at best. I know this particular teacher is very popular with students as she writes great letters and is also a mentor for an ec many of them participate in so the letter is broader than just the classroom. She’s been gracious enough to send at least 5-6 for my daughter and I know a good friend of hers has done a ton of scholarship apps, so has probably done even more for her. You have 20-30 kids asking for 3-10 letters, and it gets pretty insane pretty quickly. I better understand why the IB English teacher states the first day of junior year, that you have to apply to get a rec from her and she only writes them for a limited number of students.