Many of us have seen instances of a user asking multiple questions, often a few minutes apart. When this happens, the user usually puts little to no effort on answering the questions themselves and expect the answer to be handed to them. We definitely want users to actually think about questions before asking them, and I think it's fair to assume that if you're submitting questions one after another, you can't be thinking too hard about any single one.
I'm suggesting the implementation of some upper bound on questions asked by a user in a time frame of something like an hour. This way we could eliminate question spam from users who just want quick answers while encouraging users to think about a question before asking. This may be inconvenient to users who have many thoughtful questions, but I think that if they have a thoughtful question, they can look at that one first before asking a new one.
At worst, if this is too restrictive, I'd at least suggest a notification when a user asks a question when they've already asked a question recently, reminding the user to ask thoughtful questions, and to think about a question themselves before asking it. This wouldn't prevent a user from mass question asking, but at least it would make clear the site's expectations on asking questions.