While LORs do add to the applicant’s profile and are technically part of the teacher’s/Profs’s job, it should be said that the decision on whether to write one for the requesting is solely at his/her discretion. No student…or employee for that matter is entitled to an LOR with a particular instructor/supervisor.
If the instructor/supervisor doesn’t feel inclined to issue one for him/her*, the student/employee should seek out other instructors who know the student in more depth and/or could write a strong positive LOR in good conscience. And if s/he can’t find anyone, s/he may need to self-assess and to take some stock in asking him/herself what s/he may have done to have end up in a situation where no instructor/supervisor is willing to write one for him/her.
Also, LOR writers can and do reserve the right to take back promises to write strong positive LORs if they subsequently observe student behavior/actions which bring their prior positive impressions of his/her academic work or character/attributes into doubt. A good reason to maintain the positive impression not only with that particular Prof, but also with other Profs…especially within the same department.
An older undergrad classmate had two Profs from his Masters program rescind promised LORs after subsequently hearing about his negative classroom behavior from another Prof in the department.
- Often because the LOR writer doesn't feel s/he knows the student's work and his/her attributes/character well enough to write one or feels the student's academic work/attributes/character aren't sufficient to merit writing a strong positive LOR in good conscience.
I don’t recommend openly advertising this attitude with any faculty or supervisors you may have as a graduate student or employee as many of them do see great value in LORs.
And this value is actually higher in some professions and at the graduate level…especially PhD. In fact, for the latter, LORs are just as/sometimes more important than one’s undergrad/Master’s GPA, Master’s/undergrad thesis if applicable, etc.