Lately I have been trying to challenge myself during class, so for the last two classes I've taken, I made a rule that I would use the barre as little as possible. That doesn't sound so difficult, but I soon found out just how much I rely on the barre, even when I think I don't. A simple battement tendu exercise in first suddenly required quite a bit more effort, and it only became more difficult from there. If I truly need the barre (for a very fast exercise, or one entirely on demi-pointe, for example) I use it, but otherwise try to do without. While I'm sure it isn't as pretty to look at, I've noticed one important benefit: the less I use the barre, the better my balance is in the center, particularly during pirouettes, because there's no "adjustment" period of trying to figure out how to get to demi-pointe without support.
I'm certain I'm not the only one who has experienced this, but I think it's an idea that could be used more often in ballet classes. Even when one is doing everything right, the barre ends up providing more support than it should simply because one's hand is on it, so the dancer ends up using it more than s/he is aware. There is also a great temptation to make the barre work as clean and neat as possible, which is an appropriate goal, but not when it comes at the expense of gaining strength and balance. Barre work is a tool, not an end in itself, and if the concepts one practises there do not transfer to the center, what's the point?
Ballet class--especially barre--is always a work in progress. One isn't there to present a perfectly polished performance but to challenge oneself and grow. When creating art, one frequently has to make a mess in order to make something beautiful, and ballet is no different. So make a mistake, lose your balance, miss a pirouette, yet always with the finished product in mind. That's how you get better.