This made me think of the possibility of "spreading out" the task of answering students' messages among several instructors using WeBWorK. All that would be needed is to add another instructor (who can be located anywhere) to my course, and then I would be added as instructor to their course, so that we both receive messages from both courses. On answering a message, the other instructor would receive a copy, so that they know that the message has been answered. This way there would be a higher chance that students in both courses receive faster help.
I would be interested in knowing if this has been tried or discussed before.
I am currently teaching Pre-Calculus (College Algebra and trigonometry) with WebWork, with a total of about 60 students, and I would like to try this type of collaboration with other Pre-Calculus instructors.