My opinion is that titles should be phrased as questions at all times. Simply because it's a Q&A site. We are currently taking different paths with edits in many cases. It's still working out because 3-4 editors on a question often triples its quality, I've been happy to see all of the community effort lately.
However, I'm finding that I don't have the time to catch every title that needs improvement, and I'm probably the only one that sees it as an issue at the moment.
First, it depends on whether there is general agreement towards a consistent approach, and then there is the approach itself.
Do you agree that there should be a consistent wording format for titles?
What do you think the wording for titles should be?