On page 87, the Rules Compendium defines retraining as:
Sometimes a player makes decisions when creating or advancing a character that he or she later regrets. Perhaps a chosen power isn’t working with the character concept, or a feat never comes into play as anticipated. Fortunately, no one is stuck with bad character decisions. There’s an opportunity to change a decision whenever the character levels up.
I agree with the entire sentiment, except when it comes to the last line—and I think players should be able to retrain what they want, when they want. My only request is that I’m notified any time a feat, power, or skill is retrained.
Traditionally, I’ve been a lenient DM, playing fast and loose with rules to focus on fun—and this rule is no exception. After all, why hold a player back from retraining before the level is gained? Some campaigns level at an abysmally slow rate and a player could potentially be stuck with a bad decision for weeks on end. In addition, the retraining rules only allow you to to make one change per level, be it feat, power, or skill.
These seem like needless restrictions.
I realize this rule wouldn’t work for every group, but it works well for mine because I trust the people I game with and they know I’d beat them with a rubber hose if it were taken advantage of.