“I am thinking women are exempt by the principle “osek b’ mitzva patur mimitzvah”. Almost anything the women is doing when taking care of the house is a part of the mitzva – chesed, assisting in learning, chinuch, etc so she does not need to interrupt to do _other_ mitzvot“
We say שלא עשני אשה because don’t have to do מצוות עשה שהזמן גרמא if the whole reason is because עוסק במצוה the reason would fall off