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Most shiurim that take place in shul like daf yomi or a weekly shiur are given BEFORE Shachris or mincha without tefillin on & then upon finishing learning everyone starting to put on tefillin.
most AFTER learning shiurim are a quick 5 minute daily halacha shiur by the rav which when given is still considered part of davening & upon finishing the shiur someone says kaddish d’rabbanon