Or keep math papers single-spaced?
Single-spacing seems to keep important information together a little bit better, e.g., theorems and its proofs. While double-spacing is visually a little more comfortable to read, information such as theorems and its proofs are separated frequently, although during somewhat-lengthy discussion sections of a paper, double-spacing would be very nice for a reader.
What do you think? Is there a standard convention among math writers?