The longer a person wears his tefilin, the greater its effect on him. There are different opinions as to when a person should remove their tefilin after davening. According to one opinion, it is after the prayer of Uva Le’Tzion; according to another opinion, it is after a person has heard three Kadeishim (the Kaddish before Barchu, the Kaddish after Shemoine Esrei, and the Kaddish after Uva Le’Tzion), as well as four Kedushos. The four Kedushos are: Barchu, which is a form of Kedusha, the Kedusha Kodosh, Kodosh, Kodosh which is said in the blessing of Yotzeir Or, the Kedusha which is said in Chazaras HaShatz, and the Kedusha which is said in Uva Le’Tzion. According to another text, it is four Kadeishim (the three above and one additional Kaddish) and three Kedushos. Still, another opinion is that a person should wait to remove them until after Aleinu, even when he is praying privately, since the words of Aleinu are associated with tefilin. Many are particular to remove their tefillin only after the recital of Tehillim after davening. Some people do all of the above while wearing Rabbeinu Tam tefilin, but the proper way to is to put on Rabbeinu Tam only after all of the above have been said. There is a custom practiced by many to learn some Torah as well while wearing their tefilin.