I don't think there should be a limit. Why? Because it's a community and we should have the privilege of having the ability to ask as many questions as we want. It brings more "Mm mph" to the table and site itself.
So having the ability to ask as many question's is well worth it in my eyes. It actually makes hubpages look good in the Search Engines eyes because it's not just a site that publishes How Tos And Best Ofs it's a site with people asking real questions and real people answering them.
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