Yes. First, however, you need to define “more often”. If you are training a body part once per month, hitting it more often will certainly be more beneficial, but if you are training it once a day, more often won’t do any good. The approach of training a body-part once per week, is largely based on the training style of Dorian Yates, who deplored the practise of hitting a body-part more than once per week. If you were able to train a body-part twice, the reason was likely that your trained like a pathetic schoolboy during your initial workout. You can hit body-parts that you need to improve twice per week – first on a heavy compound day and second concentrating on more feel with volume. If a lagging body-part is weak, you can train it more often because it does not take as long as to recover.