The ability to select multiple items for scheduling
For example, it would be really useful if you could individually select numerous items in your Inbox and schedule them for the weekend. It would also be great if you could schedule all items with a particular tag in your inbox.
I agree with Dan's comment. Multiple selection of items is very necessary.
Dan Boisvert commented
I would modify this suggestion to: "The ability to select multiple items for any function", not just for scheduling. For example, if I forget to add a tag to a list of new tasks, I should be able to select all of these and add the appropriate tag to all of them at once, rather than having to add the tag to each one.