Little Known AdSense Feature

section targeting:

Just put some code similar to this on your webpage to instruct Google to either ignore or add importance to that part of your content:

-- google_ad_section_start --

-- google_ad_section_end --

(Blogger won't display the real code)

Also on the info page for this, it says:

However, please be aware that we can't guarantee results, and that it may take up to 2 weeks before our crawlers take into account any changes you've made to your site.

Is that an admission from Google that by joining AdSense you are guaranteed the spiders will visit at least fortnightly?