Repeating the B’rakah of T’phillin

Question
If I put on tefillin more than once on a given day should I say the brachot on them each time?

Answer
The Talmud Yerushalmi says that one should say the brachot on only the first time one puts on tefillin on during a given day. The logic behind this is that tefillin is a mitzvah incumbent upon a Jewish adult male during the entire day, dependent upon the circumstances. Therefore, the first time one makes the brachot they apply towards the entire day.
Indeed, the Talmud Bavli indicates that one should make the brachot on tefillin each time one puts on tefillin during the course of the day. This indeed is also a legitimate approach.