Ralph Waldo Emerson is often quoted as saying that consistency is the hobgoblin of small minds. The quote actually says that it is a foolish consistency.
In communications, consistency is a necessity. Case in point, using your logo. If you use your logo only some times, you are not building your brand identity. On the other hand, if you use your logo all the time, then you are consistently working on reinforcing your brand.
If you blog, you should blog consistently. If you abandon your blog for months, your readers will abandon you. If you run a networking group, you should have meetings on a consistent basis. If not, then your group may think you are no longer in business.
I just read this blog post about obvious tips to save you time on Unclutterer.com. In communications there may be one obvious tip to communicate more effectively: be consistent!