Article directories are a great source of information but also a great source of traffic and links from important websites to your articles.
1. Writing to article directories sends traffic to your website or blog for life as long as they are online. When people write for Ezine Articles they get traffic forever and this is great to boost their morale to continue to work.
2. Article directories boost search engine ranks as they are Do Follow links and search engines love to see lots of articles linking to home pages.
3. Article directories are a great way to boost your brand awareness
for free if you write the articles yourself.I
suggest that you write about one article per week for the ten biggest article directories so search engines will always be up to date with your blog and to keep the traffic coming. Now with Google Panda it is harder to get traffic from article directories than before but if you create consistent interesting content, the traffic will always come.
How many articles should you write for article directories? I would say unlimited but so normal human being can do that so aim for writing several per day and you will be fine.