Rav Yitzchok Isaac of Ziditchoiv zy”a related that his rebbi, the Ateres Tzvi zy”a, once asked Rav Avrohom Chaim of Zlotchov zy”a why he gave ideas for segulos to people who came to him in need of yeshuos. Rav Avrohom Chaim answered that Chazal say (Vayikroh Rabbah 10:5) that “tefillah does half”. Therefore, he suggests a segulah for the other half.
The Ateres Tzvi then said, “We daven more than is required of us, so we can do the second half with tefillah as well and we don’t need any segulah.”