In my opinion, the more important area to control was inside the French Empire. He already controlled most of Europe, and if he didn't focus on what he already had, the people in the French Empire would angry that he was neglecting the people who stuck by his side. Also, if he had controlled more of Europe, he wouldn't be able to control his other countries.
By 1812, the only parts of Europe not under his control were Britain, Portugal, Sweden, and the Ottoman Empire. Besides the French Empire he controlled many small, independent countries including Spain, the Grand Duchy of Warsaw, and multiple German Kingdoms in Middle Europe.…