Why is ad widget (sidebar) prioritized over post-body ads?

I have the plugin set to display 3 ads. The third ad is after the nth paragraph, or if there is not enough paragraphs it should default to the ad widget in the sidebar. However, the ad widget is always given priority for some reason over the ads in the text of the article. Shouldn’t the plugin take the first three ads based on where they are positioned in the html on the page? The ad widget is always the last ad in the html, so it should be omitted if there are already 3 ads in the text. Correct? Instead, it removes an ad from the content and always keeps the sidebar ad.
I have been using your plugin for years but never understood why it worked this way. Thanks.

http://wordpress.org/plugins/quick-adsense/