You are correct.
EP is not my only source for fiction - as I said, there's a core select of writers who turn up in the major magazines all the time. When you start getting "bunches" of this core in every outlet you consume, is does tend to make the industry seem a little insular.
I'm going to go away and do a little counting/statistic. Be back soon.
*edit* ok, back with my counting
Since I started listening to EP in July 2006 there have been 43 individual writers featured.
Of them:
Mike Resnick has had 5 stories (28/9/06, 30/11/06, 8/2/07. 12/4/07, 14/6/07)
Nancy Kress has had 4 stories (12/10/06, 23/11/06, 26/7/07, 27/9/07)
Robert Silverberg has had 3 stories (28/12/06, 15/2/06, 5/7/07)
Pete Butler has had 3 stories (7/9/06, 3/5/07, 7/6/07)
Tobias Buckwell has had 3 stories (3/8/06, 31/8/06, 14/12/06)
Mur Lafferty, Jeffry DeRago, Tim Pratt, Stephen Deadman, Kevin J Anderson, David Barr Kirtley, James Trimarco, Kay Kenyon, Ramona Louise Wheeler, and Heather Lindsley have all had 2 stories.
Looking at the evidence, you think I'd be saying "There's too much Mike Resnick!" However, I have no problems being bashed over the head with optimism
I don't mind multiple stories from same author, so long as they're spread out over a matter of months. 4-6 months ideal.
For example, Tobias Buckwell had two stories within the month of August 2006; Nancy Kress' stories have been within 5 weeks and 8 weeks of each other respectively; Kay Kenyon had two stories within the month of Feb 2007; Mike Resnick's stories this year have been within 2 months of each other.
Let me riterate - I am not bagging, bitching or bashing. I am merely making the point that EP combined with other outlets for these authors tend to make subjective "clumps". I'm not asking Steve to be in the pockets of other outlets to check who's publishing on a monthly basis, just that their stories are spread out more evenly, further apart (barring special months eg: Hugos etc).
Thanks for listening to me ramble.