Who says Google change their algorithm every week?

Its news to me and that would take a heck of a lot of work. I think
it more likely that your RSS content is changing, which is why your
position changes. My three sites are at #1 and #2 for their main
keywords, and have been for the last 2 years, so there is no problem
with stability. There are so many variables with respect to website
positions, the main ones that affect your SERPs being such things as
live keyword density changes such as with RSS, duplicate content
problems, such as submission of one article to multiple directories
which results in a gradual drop of PageRank votes unless you keep
topping it up with fresh articles, other sites coming online using
your keyword and so on.

I don't really think Google are going to keep changing an algorithm
that takes ages to develop. Your best bet is to use good solid SEO,
such as using your keyword in title tags on each page, page H1
headings and H2 subheadings, and also in your Meta description tag.
Don't overuse keywords in the body text (even 1% is approaching max,
and 3% is spamming) but use keywords in your first 100 characters,
above the fold and in the last paragraph. A silo site structure is
also honey to Google.

Peter

P.S.: How would you like your websites to be listed on the major
search engines within 2 days, and rise high in the listings within 2
weeks?

I never fail. For step by step instructions and screenshots of my
web pages and HTML showing how I do it check out:
http://www.improved-search-engine-rank.com