Colleges that want LoRs, especially supplemental school specific ones, should really think about the consequences of overburdening teachers or blocking some students from applying due to LoR rationing.
Or maybe that is the point to put an indirect thumb on the scale for students in elite prep schools where teachers have time for, are expected to, and are trained to write good LoRs for every student, and the college counseling staff allocates students to teachers to avoid overburdening any teacher.