I was reading this post about press releases where Dr Pete Meyers - a Seomoz Associate, was expressing his opinion about the same subject, here it is:
"I have some smaller clients who have had limited luck with it, but I think it's best to just stick to one of the sites and do periodic releases (maybe every couple of months). If nothing else, it'll give you a sense of what's working, and you can take some of the popular releases and push to get them a broader market.
What I wouldn't do is go after multiple low-value PR services and plaster the same releases everywhere you can. At best, it's diminishing returns - at worst, they'll be devalued. I'm with Peter G. - the best press release opportunities come through relationships with the media. Obviously, though, that takes a lot more time".

You opinion is that "repeatedly submitting to a the same few press release sites is not going to be a sustaining source of power.  A lot of links on the same site are not as valuable as one link on each of a lot of sites"
I do not want to question your authority or his but there is a difference of opinions from to seasoned contributors. Any thoughts about this Dr Pete?