Due to the exigencies of academic peer review, most academic presses assume (even require) that they have exclusive consideration at this [full manuscript reading] stage. It’s best, therefore, to wait to hear back from as many queries as possible before deciding where to send the full ms. It’s also best to send your query letters in batches, i.e. first-tier presses, then second-tier, and so on, so that you don’t wind up with an eager offer from a third-tier house while awaiting word from your dream publisher.

Said YellowTractor at The Chronicle’s fora