May be this is the question that one businessman least expect. Unfortunately most (we think more than 80 percent) business blogs or company blogs fail to achieve their goals, or to achieve at least a part of those. There are many things which contribute to this much failure of blogs. You never need a blog when,

• It is not based on a theme or idea.
• You don’t have time to publish posts, which can be anything interesting or informative.
• You don’t know how to market it among your customers and other web users.
• You lack ideas for new posts, and going to republish same post (idea) repeatedly.
• Your only goal is to build links to your site; submitting links to web directories and articles to article directories is a much more preferable and fair option.
• Your only goal is to enter some reciprocal linking practices, and/or AdSense income.
• You are going to publish 10 posts for one day and no post for other 6 days.
• You are going to copy paste content (posts) from other websites and blogs.
• Your blogging software is too complicated to handle and the content is not reachable for search engines.