Manually + slow may be effective, but it is not efficient. My automated + fast = more effective (since I publish to many sites at once) and more efficient because I am not manually copy + pasting the same content to different sites.
The only downside to programs is taking advantage of the extra link on some sites (like go articles) and then having only one link for some of the sites. Those are the ones that I will manually post to (especially go articles, good
PR plus a third link is a win).
The extra posting on the articles doesnt hurt anyone, it is syndication. In fact, I make sure to submit my RSS feeds (with these same articles) to other services for further links and traffic.
The only thing I really do as far as submission is that I submit to ezine articles first. If they approve it, then typically the other sites will only decline it if the word count is low or high. I could easily just blast them at once, however, as I do not get my articles declined much anymore... it is built into my routine now though.
You can make you mind on your own, but I would seriously recommend following the advise of Jim and blasting them all over. Article marketing is a numbers game, and the more numbers you have the better.