Why is it that if one recites a bracha on eating in the sukkah and then leaves the sukkah after finishing the meal, a new bracha is required at the next meal when one re-enters the sukkah; however, if one recites birchas haTorah on learning and then goes about doing other things, a new birchas haTorah is not required when one resumes learning?
Tosfos (Brachos 11b) answers that exiting the sukkah brings the performance of mitzvas sukkah to a close for that time period. However, the mitzvah of talmud Torah is an ongoing obligation which has no end. R' Soloveitchik compared it to a mother's relationship to her child: even when the mother is not actively engaged in taking care of the child, the child is still in the back of the mother's mind and a subject of her concern. There is no hesech hada'as from talmud Torah even if one closes the gemara to engage in other business.
I recently discovered (thanks to learning Halichos Beisa with my daughter) that the Tzlach writes that Tosfos' sevara is well and good for men who have an ongoing obligation of talmud Torah. However, women have no such obligation. Though they still are entitled to recite birchas haTorah (for various reasons discussed by achronim, e.g. they read and recite pesukim as part of tefilah), there is no mitzvah for them to remain engaged in thinking about Torah day and night. Therefore, the Tzlach posits that if a woman stops learning and then resumes study at a later point in the day, she would be obligated to recite a new birchas haTorah.
(I don't think this is the common practice, but you can ask your posek what he thinks.)