I realise this is a common question, but my situation is complicated by the work-related responses without a response to my reference request. I requested a reference letter from my professor a week ago, and followed up yesterday, but haven't received a response for it. I checked in with the administrator this morning to see if everything is ok but haven't received a response from him either. I did receive a prompt response (<1hr) from my professor today for an email regarding ethics approval on a project she is faculty supervisor for.
My professor has provided supportive reference letters in the past, so I am confused about how long to wait and whether I should follow up again. She did return from vacation last Monday. My other 3 referees, all directors of departments, responded within <1 hour in the affirmative so I feel like I'm a pretty good bet. The deadline for the letters is just over a month from now.