Michael Mitzenmacher writes about some job searches in computer science, including one that he chaired that was able to make 6 simultaneous offers, and ended up hiring 3 people. He argues that making simultaneous offers sends a signal. (It is certainly a signal about the support the university is offering to the department, and the direction that it is taking...)
"in our last search (which I was leading), where we ended up making 6 offers (and got 3 acceptances). We (the hiring committee) recognized that we were making a rather significant request to have 6 simultaneous outstanding offers. We also recognized the dangers in trying to sequentialize these offers. First, there was the internal danger -- the complex discussions (we had such a great committee, we wouldn't have argued) we would have had to undertake to rank-order everyone we wanted to make an offer to. And second, there's the external danger that the candidate -- who will, of course, find out they were the "second choice" -- takes the ordering as a negative signal and becomes more inclined to take another offer. One can argue whether or not a candidate should take such an ordering as a signal, or whether such a reaction is a purely emotional response. (See Mihai's post, for example, and judge for yourself in that case.) But it was clear to us that, even if no such signal was intended, there was a high risk that would be the interpretation from the standpoint of the candidate.Mihai's post provides a solid empirical data point that we were right to have this concern; it's something I will keep in mind (and if necessary point to) in future hiring discussions. I'm glad we were able to make 6 simultaneous offers, and give all of the candidates we made offers to the right signal."
HT: Itai Ashlagi, who is on the job market this year