The most common myth about womens cycles is that every woman has a 28 day cycle and ovulates on cycle day(CD) 14.
If we go by this myth and a woman has baby making intercourse on days 12, 13 and 14 but doesn't ovulate till day 20, she has missed her fertile window altogether. Or on the other hand, if she ovulates on day 10 or 11 she has also missed her fertile window.
Each woman is different and ovulation days can vary between individuals and also between individual cycles.
There are only a few ways in which ovulation can be confirmed, this is either by ultrasound, blood tests or through charting your BBT(Basal Body temperature).
Observing your cervical fluid, symptoms and using OPKs(Ovulation Predictor Kits) may indicate that ovulation is approaching but does not confirm ovulation occurred.
Many women, especially those who have been diagnosed with PCOS can have multiple patches of fertile cervical fluid and multiple positive OPKs throughout their cycle.
Using a combination of these observations greatly increases the ability to determine that ovulation is approaching and more importantly that it has occurred. Observing your cervical fluid and using OPKs can help to determine when to have baby making intercourse before ovulation is detected, whereas keeping track of your BBT can confirm ovulation after 3 temperatures in a higher range than your pre-ovulation temps.
By having intercourse anytime you notice watery or egg white cervical fluid and/or when you get a positive OPK and keep having intercourse, when possible, until ovulation has been confirmed on your chart, being either daily or every second day, will greatly increase your chances of conception.