I can report (since I do monitor these things) that releases that are not on the same day, but close in time do tend to compliment each other rather than detract in terms of audience interest. I saw more traffic starting Dec. 31, 2013 over the next few weeks, a period which saw several major releases, than at any time since I started monitoring these things over four years ago. MAJOR TRAFFIC. People watch Film A and enjoyed it, so they look for another Star Trek Fan Film. Most viewers are not into all the inter-group politics and other issues. I'm sure the major groups each have a few hundred, or perhaps a few thousand super-fans who care, but the major groups get tens of thousands, even hundreds of thousands (indeed, over time, millions) of views, and the overwhelming majority of viewers are only interested in viewing a quality product. They see one, they try another. Hence, a release of Exeter's TTI and The Holiest Thing a week or less apart might actually INCREASE traffic to BOTH.
That said, in all cases, once they are released, these things are watched for years and years. Do the job the way you want it done.
I do not by the above in any way mean to say that if somehow it could be arranged that there was one major film released at the start of each month (or mid-month) that would not also build traffic, as people would know when to look for it. But I don't see how that can be done. Potemkin seems to be in the road to fulfilling HF's shoes and has the potential for monthly releases, but how that's handled is in the end Randall Landers's decision. I hope whatever he does builds traffic.