I'm a senior undergraduate student awaiting (physics) PhD program application decisions. I spent a chunk of last summer writing to and, occasionally, informally interviewing with PIs of interest, and I ended up applying to about 18 programs. I unfortunately have not yet heard positively from any of them, and people around me are starting to suggest that this is bad news at this point in the cycle.
I understand that some of my peers have had success reaching back out to PIs of interest whom they had previously written to or spoken with to inquire about their application status (one, for instance, wrote late last night and as a result received an informal acceptance this morning). There are three or four schools, and five or six specific PIs that I am particularly interested in working with, and to whom I have previously written (all responded with some variation of "yes, I am taking students this cycle and encourage you to apply"). I'm considering writing them again to ask whether they have identified students of interest, and whether I can reasonably expect that there remains some chance I could be admitted this late in the cycle.
Would it be advisable to do so? I can imagine arguments for and against. It might show initiative, and/or remind them of my interest and existence. I know that PIs typically do not make final admissions decisions, but they often play a significant role in who does or does not make the cut. On the other hand, one could imagine that it might be seen as an annoyance. I know that professors have a lot on their plate— particularly those serving on admissions committees —and are perhaps receiving a significant amount of email from other prospective students.
It is incredibly important to me that I am admitted to a graduate program, and I'm trying to do whatever I can to make that happen. I love conducting research, am convinced that this is what I want to do with my life, and recognize that being able to do so in the subfield(s) I am most interested in and at the level I would like to is highly contingent upon receiving a PhD.