I've tried that; it works, sort of… but it isn't really a good practice.
The problem is that when you post a question or an answer, the question is listed or bumped to the top of the front page and question lists. However, when you delete that post, it continues to be listed on those pages, even though you deleted it, sometimes for hours (blame it on performance caching).
Deleting a draft question is a bit more problematic than deleting a draft answer. When a user goes to view a new question (which you have since deleted), they're going to get an error (HTTP 404). Higher rep users can see the deleted question, but it's going to look a bit suspicious, and an attentive user might be inclined to verify there isn't a more wide-spread problem (like "self-vandalism of posts").
Deleting a drafted answer isn't quite as problematic as deleting a question… because all you're doing is bumping the thread to the top of the 'activity' page (unnecessarily). But still, you're notifying potentially hundreds or thousands of attentive users to see what changed in that post… but it's a wasted effort because there's really no change at all.