I have a few twitter accounts and I have posted links in all of them. It depends on many factors such as:
1. the quality of your posts - are you only posting links or are you actually contributing to others by retweeting and responding to other - thus creating that sense of community
2. Are your links self serving or its actually helping others?
3. Type of followers
All these factors affect your click through rate in TwitterLand.
With one of my clients I use Twitter and I am getting some results now after a few months but as they are in a niche market my results were going to be slow in developing. Depending on what you are marketing and who you are marketing to, you may want to vary where you are promoting your site. My client markets high end accounting solutions to corporate customers and I am getting the results I am with twitter as well as with Linkedin.