Formally, Ketoret is said once at the beginning of Shacharit, once more at the end of Shacharit, and yet again at the beginning of Mincha.
But even saying it once a day is very powerful.
It's recommended that women say it at least once during Shacharit. Please see here for the flexible halachic requirements for women's davening:
And here: https://dinonline.org/2019/06/13/varying-the-amount-of-shacharit-said-at-home-for-women/
How does Ketoret work?
Well, the burning the Ketoret mixture had a cleansing effect on the entire area of Jerusalem. All those unseen forces and effects of tumah that can affect one’s mental and spiritual health were basically blocked by the Ketoret.
Beyond its spiritual protection, reciting Ketoret also a segula for parnasa (livelihood), health, and shalom bayit (domestic harmony).
Daily Zohar explains that Ketoret protects us by breaking klipot (negative spiritual "husks") and cleanse negative residue from our lives. This in turn can open the way for success & blessing.
Here is another important informative article on Ketoret:
The reason why spiritual cleansing is so important is because it enables us to fully cleave to Hashem without inner obstacles.
An important part of Ketoret is the inclusion of the foul-smelling chelbana (galbanum). Chelbana symbolizes the sinners. Rav Shlomo Ephraim of Luntzchitz wrote in his Kli Yakar commentary on the Torah that just as the foul-smelling chelbana can be elevated within the Ketoret to offer a beautiful and cleansing aroma, so too can a sinner elevate himself or herself through teshuvah and have his or her foul deeds transformed into sweet repentance. (Please see here: The Kli Yakar on Parshat Ki Tisa.)
For more symbolism of the Ketoret, please see here: The Kli Yakar on Parshat Titzaveh, and scroll down a bit.)
This page is definitely worth reading in full:
To give you some idea of what’s written there, Rabbi Sutton writes about Vendyl Jones's discovery of a container of the Ketoret and how they received permission from Rav Ovadia Yosef & Rav Yehudah Getz to burn it with hydrochloric acid [and not with real fire] in 1994.
The chemical burning also included Sodomite salt and Karshina lye (as stated in the Ketoret prayer), which was also found in the Qumran cave.
Shockingly, despite the 2000-year storage, the whiff of fragrance lingered for several days after the chemical burning. It also cleared the area of a variety of insects for a prolonged period after the burning, a phenomenon described in Mishna Avot 5:5.
Moshe Rabbeinu and Aharon HaKohen also used Ketoret to stop a plague. According to the Arizal, the 11 spices used in Ketoret parallel the 11 Sefirot of Tohu (Chaos) and have the power completely rectify evil by elevating it back into a state of holiness.
Gemara Shabbat 89a states that Moshe Rabbeinu learned of the power of Ketoret from the Angel of Death himself. Ketoret can nullify ANY evil decree, including death.
Again, this is because of Ketoret's power to transform evil into good.
Remember...initially, the Creation of the World was full of light. There was only good. Hashem Himself is only Good.
Evil is an aberration, a corruption. Ketoret simply returns things back to the way they were, back to the way they were originally meant to be.