By making the competition longer for entries when theres little interest you are really just dragging it out. if traffic is low, making it a longer submission time wont boost entries. Shortening the entry time will however as it may give people who are waiting for the next theme they may like an insentive to hang around or boost the number of entries as there is less waiting time.
If we only get around 3 entries, making it 7-8 days for submission will just drag things out..you probably wont get any more entries as those who wanted to enter will have already.
By shortening the time, it speeds things up, gives people more insentive to get off their butts and do something for it and if they miss out, theres always the next comp. this way will also see more popularity as the themes would be cycled through quicker sparking interest from those who are waiting for a specific theme and it also will give us more google exposure as there would be more SOTW threads for mvc meaning more hits on the search engine.
Just my opinion.
shorter entry times would be best based on the current situation...IMO.