As in, does it matter whether the professor is full time and tenured versus a visiting scholar, lecturer, or adjunct professor? I actually never considered this issue before, but I recently saw a post on StackExchange where a professor basically said that full time faculty on a tenured track have more of a “stake” in where the student ends up (it benefits the department and therefore the professor), whereas part time, temporary, or adjunct faculty might not not put as much effort into it (though I would still like to think that most of them would, but given their busy schedules…).
Is this really something I should take into account when requesting recommendation letters? I didn’t expect to, but the more I think about it the more it makes sense.
Also apparently non-full time faculty are only paid for their time teaching, so letter-writing is technically not part of their job?! (i.e. the time they spend writing the letter is not paid time) This astounds me more and more, as I’ve never had a non-full time faculty member turn my requests for recommendations down.
Any benefit of higher academic rank is by far far far far trumped by how well they know you, which usually translates into how strong a letter they can write for you. This question has been asked time and time again online and in-person to deans and other admissions committee members, and always answered the same way.
In the hypothetical situation where you know a lecturer as well as a full professor, and they would write equally strong letters, then there would be a reason to choose to send the latter’s letter over the former’s. In almost all other situations, choose the letter which is likely to be more complimentary. (Exceptions may include cases where one person is a very well-known name in the field such as a Nobel laureate in Physiology or Medicine, or where one person personally knows the dean of admissions of a medical school.)