I agree. Getting to sixth level in 3.5 D&D does happen relatively quickly, but I wouldn't slow advancement to such a crawl. Character advancement is one of the main driving factors of D&D. It is one of the most entertaining and rewarding aspects of playing. If you have to play once a week for hours at a time for 6 months to get from 1st to 2nd level, you have removed one of the most enjoyable aspects of the game. That may work for you and your group, but it will most likely be rejected by most groups. "Freezing" advancement in the 6th to 9th level range preserves the "sweet spot" of the game.