Actually, quantity is not really the point in link building. Search engines do value greatly the relevance of your backlinks with regards to your site than the quantity of links you have. The objective in link development is to obtain a relevant links. Don't waste your time looking for MORE links, just look for some relevant one.
Look for good links, more than numbers. There are no completely natural patterns as many sites get a few links a day or less, but the right blog post might generate hundreds in hours. The exact same number everyday would really seem odd though.
If you want to be top ranked, go for quality not quantity. The best way is to look at a high page rank site. Many have only a few hundred links but they link to relevant sites. Then look at their keywords. Some use very little key words in the META tags to increase density. Link to good links. The best links are one-way permanent links. Directories help out a lot.
[edited by: tedster at 5:46 am (utc) on Mar. 12, 2007]