Search engine optimisation is always moving, when google changes its algorythm or yahoo updates its software or MSN merges with another company all your SEO efforst must be reviewed and where appropriate updated. This in my opinion is why we will always need SEO specialists and software to help us optimise our sites. Do you agree?
That's a very good point. Rules of this game keep changing and what works today may not work tomorrow. Best SEOs are the ones that keep themselves up-to-date with current methods.