Actually you can do more than one lesson a day if you do these well written free courses. Not sure why they don't publicize them more. Oh, and CM ratings are just a way to keep you motivated. They tell almost nothing about your chess ability; it's just a fun way to learn. Enjoy!
http://www.chess.com/blog/webmaster/free-chess-mentor-courses
I greatly enjoy my daily Chess Mentor exercise, so I was a bit disappointed today when after the first move (basically a choice between 2 pawn moves, both of which work but one is slightly better) there followed 9 (!) free moves, and the lesson was over! So that was +18 (I chose the weaker 1st move) for basically nothing ... gaining rating points on CM is often ridiculously easy in comparison to TT! Notwithstanding, it's a great feature.
http://www.chess.com/chessmentor/view_lesson?id=6146