If the follicle has ruptured and the egg has been discharged, intercourse within 24 hours is certainly useful. Because after the egg is released, it can survive for 24 hours, and after intercourse, the sperm is ejaculated into the vagina and reaches the fallopian tubes in 6 hours at the longest, so that the sperm and the egg will have the chance to combine, and so pregnancy will result. If you have intercourse 24 hours after the follicle has ruptured, the egg will die and intercourse will not result in pregnancy. Therefore, if you want to plan a pregnancy, you will get pregnant if you have intercourse within 24 hours of the follicle rupturing, and you will not get pregnant if the egg dies after 24 hours.